History Literature / Animorphs

It supplanted ''{{Goosebumps}}'' as the most popular children's book series of the mid-1990s till the Millennium despite its incredibly dark setting and content, or perhaps because of it. Like Creator/JKRowling, the author credits herself as Creator/KAApplegate to [[MoustacheDePlume obscure her gender]]; the books were co-authored by her husband MichaelGrant, [[Literature/{{Gone}} an accomplished author]] [[Literature/{{BZRK}} in his own right]], and most later books were ghostwritten so that Applegate could write ''{{Everworld}}''. Applegate did still write the outlines, however, and she came back for the two-book finale.

Five teenagers discover that [[TheVirus parasitic aliens]], Yeerks, are secretly infiltrating Earth by [[PuppeteerParasite taking over people's minds and bodies]]. They encounter a good alien, an Andalite named Elfangor, who gives them the power to [[VoluntaryShapeshifting morph into any animal they have touched]]. Joined by Elfangor's younger brother and unable to trust almost anyone else, they begin a violent and secretive [[LaResistance guerrilla war]] against the alien invaders.

->''"The thing you've got to know is that ''everyone'' is in really big trouble. Yeah. [[TheFourthWallWillNotProectYou Even you]]."''

->''"The thing you've got to know is that ''everyone'' is in really big trouble. Yeah. Even you."''

The franchise included fifty-four regular installments, four extra-length specials (the ''Megamorphs''), two ''ChooseYourOwnAdventure''-style books (which are almost universally agreed to be SoBadItsHorrible), four backstory specials (The ''Andalite'', ''Hork-Bajir'' and ''Ellimist Chronicles'' and ''Visser''), a [[Series/{{Animorphs}} short-lived TV series adaptation]] by {{Nickelodeon}}, and [[LicensedGame Game Boy and PC games]]. A re-release of the series began in [[http://www.hiracdelest.com/blog/?p=543 summer 2011 with new 3D/animated covers,]] rewriting some of the more dated elements and also clearing up some {{Continuity Drift}}. Unfortunately, the lack of widespread marketing and poor sales of the rereleases [[http://www.hiracdelest.com/blog/?p=4491 led to its cancellation]].

''[[TrademarkFavoriteFood "Cinnamon BUN-ZUH!"]]''

The franchise included fifty-four regular installments, four extra-length specials (the ''Megamorphs''), two ''ChooseYourOwnAdventure''-style books, four backstory specials (The ''Andalite'', ''Hork-Bajir'' and ''Ellimist Chronicles'' and ''Visser''), a [[Series/{{Animorphs}} short-lived TV series adaptation]] by {{Nickelodeon}}, and [[LicensedGame Game Boy and PC games]]. A re-release of the series began in [[http://www.hiracdelest.com/blog/?p=543 summer 2011 with new 3D/animated covers,]] rewriting some of the more dated elements and also clearing up some {{Continuity Drift}}. Unfortunately, the lack of widespread marketing and poor sales of the rereleases [[http://www.hiracdelest.com/blog/?p=4491 led to its cancellation]].

* Animorphs/{{TropesA-H}}
* Animorphs/{{TropesI-P}}
* Animorphs/{{TropesQ-Z}}

* Animorphs/TropesA-H
* Animorphs/TropesI-P
* Animorphs/Tropes/Q-Z

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[[folder:A-D]]
* AbortedArc:
** Book 41, "The Familiar" centers on a BadFuture where the Yeerks have conquered Earth--Marco is Visser Two's host and is in charge of Earth, Cassie is a jaded terrorist and member of a resistance lead by Tobias, using the morph as Ax and looking like Elfangor, Ax is a Yeerk general that conquered the Andalite homeworld, and Rachel is crippled. The only free member is Jake, who tries to figure out what's going on. Even in-universe the world doesn't make sense though, such as how Cassie at one point uses thought-speak while human and Tobias stating that Jake is supposed to be dead, and it's revealed to be AllJustADream. As Jake awakens he hears an entity speaking that humans require "more study", implying it was a vision from the entity. Nothing in the book ever comes into play in the rest of the series and the mysterious entity is never mentioned, though it is known that it isn't the Ellimist or Crayak.
** A few off-hand references are made to the Yeerks having some presence on the Andalite homeworld, but this never developed into anything and by her own admission Applegate just forgot about it.
* AbsenceMakesTheHeartGoYonder: Marco's dad eventually gets over his wife's death... only she [[FakingTheDead isn't really dead]].
* TheAce: In-universe, Jake is seen as this. Whether or not he actually qualifies is a little more ambiguous.
* AchillesHeel: The two-hour time limit for the Animorphs. The Yeerks also have a weakness: they need to absorb Kandrona rays every three days.
* AchillesInHisTent: Jake, for a couple books in the final story arc. [[spoiler:Though he's actually angry at ''himself'', as he failed to keep his parents from being infested. In his mind, he's unfit to lead. When he does come back as leader, his personality has changed considerably...]]
* AChatWithSatan: Rachel's discussions with Crayak and the Drode.
* ActionGirl: Rachel. Cassie as well; she doesn't have Rachel's BloodKnight tendencies, but she could more than hold her own in combat. Loren in ''The Andalite Chronicles'' is especially impressive given that she has no special powers.
* AdultsAreUseless: Eventually averted once they find adults they can trust not to be infested. This ends in [[spoiler:them getting the support of the government and becoming much more effective.]]
* AffablyEvil: [[spoiler:The original]] Visser One [[spoiler: who uses Marco's mother as a host]] comes across as a friendly ReasonableAuthorityFigure compared to Visser Three, although that's not saying much. In one of the prequel books, Visser Three himself seemed to fit this when he was younger/in his earlier host body, prior to becoming an EvilOverlord.
* AFormYouAreComfortableWith: The kids never find out what the Ellimist really looks like, as he usually takes a humble, benign human shape. The reader does get a vague and incomplete description of Ketrans in ''The Ellimist Chronicles'', and the Ellimist says, after his ascension, that he chooses the humble form of a mere Ketran (in contrast to the [[EldritchAbomination terrifying, monstrous form Crayak chooses.]]) The cover of ''The Ellimist Chronicles'' most likely shows the Ellimist's favored form.
* AlienAbduction: The Skrit Na abduct and experiment on humans for unknown reasons.
* AlienAnimals:
** Turns out domesticated dogs resulted from [[spoiler:the Chee binding the Pemalites' essence with wolves.]]
** Megamorphs #2 reveals that [[spoiler:broccoli]] is another example.
*** In an interview, KA implied that ants evolved from [[spoiler:the Nesk]]
* AlienAmongUs: Ax.
* AliensAreBastards: Fairly obvious with the Yeerks, but the Andalite case is far more interesting. In the beginning of the series, kids look up to their erstwhile saviors, the great and glorious Andalites, and are counting on them to swoop in and save the day. It becomes increasingly obvious, however, that Andalite military command couldn't care less about humans. In the end, their strategy for for winning the war was to ''bombard Earth from orbit'' to take out as many Yeerks as possible.
* AlienArtsAreAppreciated: Ax's favorite TV show is "These Messages", aka commercials.
** Ax and TV in general. But partially subverted in that Ax hates all human music.
* AlienBlood: Andalites' is dark blue, Hork Bajir have black, Taxxons have a sickly yellow.
** In ''The Andalite Chronicles'', Elfangor and his friend even reference how strange and unnatural they think red human blood is.
* AlienInvasion: Yeerks invade Earth, and the Helmacrons ''try'' to...
* AlienSky: The Andalite homeworld has a red and gold sky with multiple moons. The Yeerk homeworld has a green sky and constant thunderstorms. In ''The Andalite Chronicles'', Loren, Elfangor, and Sub-Visser Seven create a weird hybrid of their respective homeworlds, and the sky is a patchwork of three different kinds of sky.
* AliensSpeakingEnglish: Subverted, lampshaded, and played straight in various cases.
* AliensStealCable: And record every channel! The Andalites apparently show TV programs like the news and MTV in school as part of learning about humans. At one point Ax, apparently not content with free-to-air TV, actually does steal cable.
* AllMenArePerverts: {{Justified| Trope}}; the main characters are all teenagers, after all. Marco's libido is often brought up, and he does everything from [[GirlOnGirlIsHot trying to get Cassie and Rachel to make out]] to using the internet to [[TheInternetIsForPorn look up scantily clad women]]. Jake makes fun of Marco for it, but when Cassie's in a bikini, Jake [[MyEyesAreUpHere can't stop staring]]. Even Ax is portrayed as being a poor student because he's always thinking about girls (he's a teenager too, albeit an Andalite teenager). [[ChivalrousPervert Tobias is the only one unaffected, most of the time.]]
--> ''<I am never a Peeping Tom,> I said way too quickly, then added, <I cannot use my superpowers for evil.>''
** He's affected by other things. In "The Pretender," when he watches Rachel transform into an eagle, he gets waaaaay too into it.
* AllPartOfTheShow: #14, on a haunted house ride.
* AllPlanetsAreEarthLike: Mostly averted, with similarities generally being more by analogy, such as Andalite vs. Earth grass despite theirs coming in shades such as red.
** The Yeerk planet is completely different and unpleasant. Fittingly.
* AllPowerfulBystander: The Ellimist and Crayak. If one of them tries to do something, the other will fight right back to counteract them. Last time they went all out, a good chunk of the galaxy was destroyed. Now they mostly just sit back and play [[TheChessmaster Chessmaster]].
* AllTherapistsAreMuggles: Cassie tries but mostly the characters are on their own. Marco [[LampshadeHanging lampshades]] the impossibilities of telling a professional therapist about their problems: "Hello, Doctor Freud? My dad's thinking about remarrying. See, he thinks my mom is dead, but she's not. She's actually a slave to an alien race trying to take over the planet. And did I mention that I'm fighting this alien invasion myself? That I do it by turning into animals? Say what? [[GoAmongMadPeople What size straitjacket do I wear]]?"
* AllUpToYou: Cassie has two or three of these.
** Take, for example, #29, The Sickness, in which everyone gets a fever but her; and #44, The Unexpected, in which she gets separated from the others on an airplane flight to Australia.
* AlternateContinuity: The ''Alternamorphs'' series featured two books, ''The First Journey'' and ''The Next Passage''. They were structured in the form of a ''ChooseYourOwnAdventure'' type story. In the first book, the reader became part of the group that gained the morphing power from Elfangor and joined the Animorphs on their first adventure. Upon completion of this, the story continued with an adventure involving a ''Sario rip'' (rip in time). The second book involved elements from two different ''Animorphs'' stories from around the midpoint. However, the books were structured in such a way that only a single set of possibilities allowed you to continue the story. Perhaps, for this reason, the series never really caught on, has been largely forgotten, and was discontinued after the second book.
* AlternateHistory: ''Megamorphs #3: Elfangor's Secret'' and ''Megamorphs #4: Back to Before'' both play with this. In #3, they follow Visser Four with the Time Matrix and experience him changing the outcome of battles and other historical events to his benefit. In #4, the Drode lets Jake see what it would have been like if they had never been given the morphing powers.
** #41 ''The Familiar'' is also an example: Jake goes to a potential future.
** Predating all these examples is #07 ''The Stranger''. Animorphs was fond of this trope.
* AlwaysChaoticEvil: Tends to be strongly subverted. Every time an apparently AlwaysChaoticEvil race is introduced, it quickly becomes clear that something more is going on.
** The Howlers are the army of doom of Crayak, a malevolent [[SufficientlyAdvancedAlien god]]. A hive-mind, they've destroyed countless worlds without hesitation. The twist? [[spoiler:They never knew killing was wrong, or that other races didn't like to be killed. They are perpetually innocent, like small children, and killing is their "game". Their collective memory is culled when necessary to preserve their naivete. Then Jake manages to sneak a memory of him kissing Cassie into their hive mind. They then try to kiss everything in sight rather than massacre it.]]
** Hork-Bajir: Eight-foot walking razor-bladed lizardmen, who appear bred purely for combat. Turns out they're {{Gentle Giant}}s, vegetarians in fact (the blades are used to harvest ''bark''), used as host bodies by the Yeerks for their brute power. Which brings us to?
** Yeerks: Literal brain-slugs who control your mind. But the Yeerks were largely pushed towards conquest by a hatred of their standing in the galaxy. In their natural state, they're 2-inch slugs, doomed to a blind, drab existence unless they take host bodies. Most, at least the ones we see on Earth, have embraced conquest, but there are a few who cooperate with the host rather than completely controlling it, and even fewer who are actively against the invasion. They're [[AlwaysChaoticEvil Often Chaotic Evil]], but not always. Even those who have embraced the imperialist philosophy don't see themselves as evil, just doing what they naturally do (you don't think of yourself as evil because you kill and eat pigs, do you?); this mindset has been drilled into them with Yeerk Empire propaganda since birth.
** Then there's the Taxxons, who [[spoiler:turn out to be intelligent beings trapped in bodies that are slaves to hunger, to the point that one recently disemboweled Taxxon is seen ''trying to eat his own entrails'' before he dies. They only let themselves be enslaved by Yeerks in exchange for a continuous supply of food.]]
* AmbiguouslyGay: Gafinilan and Mertil. They either have a very close and important friendship or the most well-written romance in the whole series. We don't get definitive evidence either way.
* AmicablyDivorced: Variations: Rachel's parents, Dan and Naomi, are uncomfortable spending time together, but they'll do it. On the other hand, she's friendly enough with Jake's parents (her ex-husband's brother and his wife) that she'll dog-sit for them when Jake's mom's grandfather passes away, while she and Jake still refer to each other as "aunt" and "nephew." And on the ''other'' hand, she and Saddler's parents don't really get along, but her family still "helps out" once he's in the local hospital.
* AnAesop: Several, including WarIsHell, and WhatIsEvil.
* AndCallHimGeorge: [[spoiler:The Howlers.]]
* AndThenWhat: The characters often try to convince themselves, and each other, that after they've saved humanity from a race of alien parasitic monsters, they'll just go back to being regular kids. Yeah, right.
* AndIMustScream: If you're infested by a Yeerk, then your memory and body is completely at his command... And it leaves your mind and intelligence intact, completely unable to do anything other than watch your "guest" do all sorts of horrible things. The Yeerks themselves suffer this in their natural state, being blind, mostly deaf slugs who just happen to be sentient.
* AndTheAdventureContinues: The series ends after a couple of timeskips with Marco, Jake and Tobias heading into a battle while in search of Ax.
* AnimalMotifs: Each of the Animorphs has a few favorite morphs that they use consistently, particularly in battle, that tends to say something about their personality and fighting style. For instance:
** Rachel's favorite battle morphs are [[BearsAreBadNews grizzly bear]] and [[WarElephants elephant]], neither of which is particularly subtle or defensive.
** Jake's favorite battle morph is a [[PantheraAwesome tiger]], which is known for its intimidating appearance.
** Marco, the clever one, uses a [[KillerGorilla gorilla]], one of the [[EverythingIsBetterWithMonkeys few animals that can manipulate things and use tools]].
** Cassie purposely chooses a [[BigBadassWolf wolf]] morph for combat, even after she acquires far more powerful animals, as she hates fighting and prefers not to seriously hurt her opponents.
*** Later in the series her Hork-Bajir morph become her default battle morph; morphing a sentient being despite her convictions that it is wrong to do so represents the conflict between her role in the war and her pacifist nature.
** And obviously, Tobias is the [[BigBadassBirdOfPrey hawk]]. Even after he regains his morphing ability, he often goes into battle in his [[ShapeshifterDefaultForm now-default hawk form]].
** Ax also often goes into battle unmorphed, since Andalites are plenty dangerous in their natural state (''extremely'' sharp tail blades, remember?)
** David has the [[LightningBruiser lion]] and the [[YouDirtyRat rat]] - the lion represents his [[KingOfBeasts savage fighting style]], as even Jake in his tiger morph couldn't defeat him, while the rat represents his [[AmbitionIsEvil cunning and self-serving nature]].
** When Tom acquires the morphing power late in the series, the only morph he is ever seen using is a [[ScaledUp cobra]]. This is incredibly fitting, given [[SmugSnake his role in the final story arc]].
** Finally, Visser Three has a grab bag assortment of alien morphs, but the only one he uses more than once is the 'Eight', the bizarre eight-headed, [[MultiArmedAndDangerous eight-armed]], [[VertebrateWithExtraLimbs eight-legged]], [[KillItWithFire fire]]-[[BreathWeapon breathing]] [[OneWingedAngel abomination]] he uses in the climax of the first book. Besides setting up the Visser as an alien threat of monstrous proportions, this particular morph owes a lot to the [[Literature/TheBible Beast of Revelations]].
* {{Animorphism}}: The TropeNamer.
* AntWar: Done intentionally to get ants off an unconscious Rachel.
* AnyoneCanDie: Death of named characters is incredibly rare before the final arc begins, particularly if the character has appeared in more than one book, but quite a few of the supporting characters ([[spoiler:Jara Hamee, Tom, Edriss, Arbron, James, and the Auxiliary Animorphs]]) [[spoiler:and two of the main characters]] ([[spoiler:Rachel and Ax]]) are dead by the series' end.
* ArchEnemy: Visser Three to the group collectively, although especially to Ax. And to Elfangor, before he died. Then there's Crayak to the Ellimist, Taylor to Tobias, and [[spoiler: David]] to Rachel.
* ArsonMurderAndJaywalking: In ''Visser'' the charges against the former Visser One are read during her trial, followed by the different forms of death penalty associated with each crime. It ends almost incongruously with "... treason by murder of subordinate Yeerks, which carries a sentence of exile to punishment duty."
* AscendedExtra: Eva, Naomi, Peter, Toby, Tom and Erek.
* AscendedFanboy: The Ellimist, arguably. [[spoiler: He starts out as a gamer on his homeworld and eventually turns into a near-omnipotent being playing "games" with Crayak.]] Also the campers from ''The Resistance'', who are Star Trek fans on their yearly camp out to look for aliens or something. Not to mention Erek.
* AskAStupidQuestion: During one of the Megamorphs books:
--> '''Rachel:''' No way. ''George'' Washington?
--> '''Marco:''' Jake, tell her, "No, ''Guido'' Washington."
--> '''Jake:''' Marco would like me to pass along a sarcastic remark.
* AssimilationBackfire: By morphing a Howler, a race of {{Psychopathic Manchild}}ren with a species-wide HiveMind (anything one sees, all of them know), Jake manages to implant the memory of his and Cassie's FirstKiss. [[BigGood The Elllimist]] tells him that the next time they're deployed, they'll try this novel tactic, which will ensure that [[MinionWithAnFInEvil they will never be used as shock troops again.]]
* AsskickingEqualsAuthority: Visser Three, in ''The Andalite Chronicles'', is a Hork-Bajir Controller with the respectable rank of Sub-Visser Seven. He's promoted to a low Visser rank immediately upon (and explicitly because of) his infestation of Elfangor's commanding officer and becomes the only Andalite-Controller in history. His rise turns meteoric from there.
* AuthorityEqualsAsskicking: Visser Three.
* AwfulTruth:
** A major motif in this series is the fact that there are some things that you just can't unlearn. The kids can't, although they desperately want to, forget about the Yeerks and go on living their lives, because they now know they'd be dooming the entire planet to enslavement; to quote a Megamorphs back cover, "You can't close your eyes to the truth you know is out there".
** Subverted in one instance, when Jake strikes a deal with Crayak to return them to the moment where they chose to walk through the construction site (where they met Elfangor and learned of the invasion). [[ItsAWonderfulPlot The kids walked home the safe way and consequently they had no knowledge of the Yeerks or the invasion]]. But, true to the theme of the series, the kids eventually have to confront the reality they didn't even know was there (made even cooler because now they don't have any powers).
* AxCrazy: [[TortureTechnician Taylor]]. And probably Rachel. No, Ax is not Ax crazy. (He may ''act'' crazy around certain foods, though.)
** David in ''The Solution''.
** Visser Three, all the time.
* BadassCrew: The Animorphs.
* BadassTeacher: Quiet, unassuming Mr. Tidwell is actually a revolutionary fighter who has a symbiotic relationship with the Yeerk inside his head.
* BadassNormal: Loren, Naomi and Eva.
* BadBoss: Visser Three (promoted to Visser One during the series). Not only does he sarcastically mock his subordinates, but he kills them for little-to-no reason. Didn't kill the Animorphs? Decapitated. Made a mistake? Decapitated. Interrupted the Visser? Decapitated. Closed a door too slowly? De-fucking-capitated. You can't win with this guy, to the point where Yeerks pass over promotions because it means having to work with Visser Three, and therefore probably being decapi-[[KilledMidSentence SLASH- *thud*]]. {{Lampshaded}}: Jake points out that Visser Three's tendencies to kill his subordinates make them hate and fear him, making him (and them) less effective. He also says that that gives the Animorphs an advantage over him.
* BadFuture:
** There's two. The "Yeerks-have-won" future shown in ''The Stranger'' and the "Yeerks-have-won-but-some-of-us-still-fight" future shown in ''The Familiar''.
** Subverted in Megamorphs 4. [[spoiler: It looks like the Yeerks are going to win, but they don't. Of course, there are millions of human deaths, so it's [[BittersweetEnding far from a good future]]...]]
* BattleCry: Rachel's "Let's do it!" and the Hork-Bajir "Free or dead!"
* TheBattlestar: Both the Blade ship and the Pool ship qualify (the former is a battleship, the latter is more of a barracks and AirborneAircraftCarrier with ''big fucking guns'').
** On the Andalite side, we have the Dome ship, with the titular domed reproduction of the Andalite homeworld that detaches for greater maneuverability in combat.
* BalanceBetweenGoodAndEvil: The Ellimist and Crayak tie each other's hands as to what they can or cannot do. If one wants something, they have to make a concession. Both do plan on eventually defeating the other forever, however.
* BearsAreBadNews: Rachel, always on the edge between ActionGirl and BloodKnight, loves her grizzly morph. The characters consider their polar bear morphs to be their most dangerous, with good reason. [[spoiler:Rachel was killed by a Yeerk in polar bear morph.]]
* BeautyIsNeverTarnished: Rachel, as a human, according to everyone else. But her morphed battles have included chewing through her own tail and whacking {{Mooks}} with her own severed arm.
** Averted in #41: When a grown-up Jake encounters the future version of Rachel, she is severely crippled: One of her arms has been cut off, both her legs are missing, she's missing an eye and her face is grotesquely scarred.
* BeCarefulWhatYouWishFor: In the first book, Tobias states he's alright with his red-tailed hawk morph and ''doesn't want to be anything else''. Consequently, the end of that episode (and the whole rest of the series) sees him trapped that shape.
* BeePeople: The Helmacrons.
* BelligerentSexualTension: It's hinted that Rachel and Marco's playful rivalry in the early books might be this, particularly on Marco's part. It begins to take on much darker and nastier undertones as the war wears on.
* TheBerserker: Rachel, at times.
* BerserkButton:
** Tom's status as a Controller was always a source of tension, but it doesn't really reach boiling point until the second-last book:
---> '''Marco:''' ...We'll be sitting ducks if Tom turns the Blade ship on us, and we all know that's his plan.
--->'''Jake:''' It's not Tom! ''IT'S NOT TOM!!'' It's not Tom, don't ''call'' him that! It's the Yeerk, it's the Yeerk in his head, ''NOT MY BROTHER!!''
** Also [[BloodKnight Rachel.]] May God help you if you mess with her boyfriend.
** Never, and I mean NEVER get in Ax's way if he wants the delicious and narcotic food he loves SO much...cinnamon buns.
* BewareTheNiceOnes:
** Human-Controllers (Yeerk hosts) generally have public personae falling between "normal but caring human" (Chapman) and "FriendToAllLivingThings" (William Roger Tennant). The Sharing, "a Boys & Girls Club for everyone" responsible for a great deal of youth work and charity events, is a Yeerk front organization intended to recruit new Controllers.
** Cassie, who is dangerous exactly ''because'' she's nice. Remember, she felt it would be kinder to [[spoiler:trap David in rat morph on a tiny rock-island in the middle of the ocean instead of just killing him]]. She also lets Tom [[spoiler:escape with the morphing cube, because Jake, his own brother, would have had to kill him to get it back,]] which caused Ax to wonder if Cassie could be more dangerous than [[BloodKnight Rachel.]]
* BigBad: Visser Three takes this role for most of the books, as the leader of Yeerk forces on Earth.
** BiggerBad: Visser Three's the main villain of the series, but he does have mostly off-page superiors, namely the Council of Thirteen and Visser One [[spoiler:(the original, before he takes her position)]], and then there's [[EldritchAbomination Crayak]]...
* BigBadassBirdOfPrey: A common morph for all six, although Tobias is [[ShapeshifterModeLock stuck in his.]]
* BigBadassWolf:
** All the Animorphs except Tobias and Ax have wolf morphs. Cassie uses hers as her main battle morph.
** There's also a real big badass wolf, who almost threw down with Jake in a battle-of-the-alpha-males for territorial supremacy in book 3. And then later he almost kicks the shit out of a Controller Jake in book 6 when his Yeerk tries to escape by morphing to wolf.
* BigBrotherInstinct: Tom does everything he can, which isn't much, to keep his brother from being infested and goes nuts at the thought of the Yeerks getting to Jake. Jake displays a similar protectiveness towards Tom besides being younger. Also, Elfangor towards Ax.
** At one point in the series, when Jake and Controller Tom are talking (which they do often, being brothers, obviously), "Tom" lies to Jake to cover his status as a Controller, and, if only for a second, Jake notices Tom's face twitch strangely. Jake suspects that Tom is trying so hard to fight against his Yeerk that he momentarily wrestled control of his body away from the Yeerk, which is pretty much established as impossible.
* BigCreepyCrawlies: The Taxxons.
* BigDumbBody: Why the Yeerks took the Hork-Bajir.
* BigEater: Ax, in human morph. Also the Taxxons, although their example is not meant to be funny.
* BigNo: David, [[spoiler:after he is trapped as a rat.]]
* BittersweetEnding: While the war is over and things are looking up for humankind, [[spoiler: Rachel and Tom are dead, Tobias has fled to the woods, Jake's guilt continually drives him deeper into depression, Cassie has had to leave Jake and the Animorphs behind in order to move on, and even Marco's happy rock-star life is bittersweetly shallow]]. Ax seems comparatively well-off to begin with, being [[spoiler: promoted directly to Prince in the Andalite military and later given his own ship to command]], but [[spoiler: his capture and apparent assimilation by the new BigBad is what leads to Jake, Marco and Tobias flying off into space and running headlong into the BolivianArmyEnding]].
* BlackAndGrayMorality: A major theme in the books. Definitely applicable by the end of the series. Can also cover the Andalite military, who are just as bad as the Yeerks, just in a different way.
* BladeBelowTheShoulder: Hork-Bajir.
* BlessedWithSuck / CursedWithAwesome: By the end of the series, everyone is either one or the other ''or'' bits of both. (There has been quite a bit of discussion about this.)
** RE: Blessed With Suck - The Taxxon's [[ExtremeOmnivore insatiable hunger]] certainly fits. The Yeerks' parasitism, which is all fine and good until one ''becomes conscious'' of one's status as a parasite. The morphing power itself may qualify, as once the kids gain it, they can't really enjoy it as they're caught up in an interplanetary war.
*** Andalites and their thought speak. It's cool being partially psychic, but the lack of mouths meant it took the Andalites centuries to develop alternatives to things like telephones.
** RE: Cursed With Awesome - The whole Animorphs gang, really. And at least Tobias was stuck as a hawk, not a flea. Or a [[RewardedAsATraitorDeserves rat]].
*** The Yeerks make the Hork-Bajir CursedWithAwesome as well. They're used as shock troops for combat because they're strong, agile, and just about every moving part on their body has a wickedly sharp blade sticking out of it. The thing is, those blades? Uninfested Hork-Bajir use them to ''harvest tree bark'', their main food source. The whiplash musculature and quick movement come from the fact that they're an arboreal species that prefers to avoid predators entirely, rather than fight off attackers.
* BloodKnight: Rachel tries not to fall into this. More often than not, she fails horribly. During ''The Separation'', when she gets split into two different personalities, one of them is a BloodKnight personified, interested ONLY in fighting. She's still somewhat interested in Tobias while like this, but that interest takes a secondary seat to violence.
--> "It was a scene of perfect beauty. Blood slicked the concrete. Taxxon guts lay in steaming piles. There were bellows and cries of pain. Battle! Desperate and deadly! I almost cried at the sheer loveliness of it."
---> -- The Separation.
* BluffTheEavesdropper: Once the team realizes how unstable and dangerous David is, they sometimes do this while discussing their plans, in case he is eavesdropping on them in morph.
* BluntMetaphorsTrauma: Ax.
* BluffTheImpostor
* BodyHorror: Most of the morphing is this, except for Cassie, who has a talent for it.
* BolivianArmyEnding
* BondOneLiner: Visser Three.
* BoredWithInsanity: The kids remark from time to time that they only thing they find strange anymore is that they don't find anything strange anymore. Constantly {{lampshaded}} by Marco, who often remarks, deadpan, on how utterly insane their lives have become.
** Let's see: started with aliens, added shapechanging, destroyed some spaceships, traveled through time...again, manipulated by god-alien, bartered hair and holograms for tour guide on distant planet, the oatmeal issue...and that's just the beginning.
* BreakTheGameBreaker: The Animorphs get the chance to acquire dinosaur morphs when they go back in time; the ending provides a {{Snapback}} so that they cannot use these morphs in the future; random TechnoBabble at the end of the book gives us an explanation why.
* BreakingSpeech: SixthRangerTraitor David in his attempt to break Rachel's will to fight.
* BreatherEpisode: The series has had a couple.
** Book 51 is a pretty good example. The two episodes right before it and the three right after it were some of the darkest books in the series, filled with emotional trauma and huge changes to the status quo. Book 51, on the other hand, is basically one big chase scene, and although it does change the status quo some when [[spoiler: the Yeerk invasion is made known to the public]], it doesn't end up mattering too much.
** Another good example is Book 20. It came right before two of the darkest books so far and right after The Departure, a WhamEpisode. However, the book itself is pretty light and primarily funny rather than dramatic.
** Book 32 stands out for being relatively light, compared to the thee books before it (many of which were on the borderline of Wham Novels), and other than introducing the AMI, it didn't introduce much to the continuity.
* TheBridge: The Pool ship's bridge and the Blade ship's bridge are the locations of some very important events.
* TheBrute: During the last story arc and the books leading up to it, the kids reflect that Visser Three is an incompetent tactician and instead relies on technological advantages; he's pushed for all-out war since the beginning. "[He] doesn't know tactics," Jake says, "he fights with a sledgehammer."
* BrotherChuck: Hey, remember Mertil, the Andalite that had also survived Elfangor's ship's crash and had been living on Earth for the entire war? Remember how he was found by the kids and decided to remain in hiding? Or maybe you don't, because he was only in one book. Having another Andalite on board would've been very useful for the kids. ''Even if'' Mertil didn't join the kids for his own reasons, it would've been nice for him to get another mention, seeing as an Andalite war hero living on Earth is kind of a big deal.
* BrokenMasquerade: [[spoiler:James and his friends, the Carpenters, and the Animorphs' parents. The kids' parents have a very difficult time adjusting, except for Eva, who adjusted a long time ago.]] This escalates to [[TheUnmasquedWorld the entire world]] when [[spoiler:open war is declared]], especially in the last book of the series.
* BrokenPedestal:
** For Jake, at least:
--->''"It's all your fault! I used to see you as a hero, Elfangor. A leader. But the truth is you just couldn't see another way out! You sentenced us to hardship and pain and suffering. We were just ''kids''! You made us question every value we had ever learned! You had no right to heap that weight on us, huge and impossible. You used us!"''
** Andalites in general for all of the kids.
* [[BreatherEpisode Breather Novel]]: Book #24, The Suspicion. Tiny aliens invade Cassie's barn and try to steal the morph cube. HilarityEnsues. Made all the more blatant as a breather because it comes right on the heels of a major [[WhamEpisode Wham Novel]].
* BringHimToMe
* BromanticFoil: Marco to Jake.
* ButterflyOfDoom: Visser Four in ''Elfangor's Secret''.
* BulletTime: A trick frequently used by Creator/KAApplegate; when one of the characters are on the edge of death, in battle, time seems to slow down. It's never explicitly ''called'' bullet time, though.
* BugWar: The war on the Taxxon planet in ''The Andalite Chronicles''.
* ButNotTooBlack: Inverted in the relaunch of the series, with fans complaining because the model chosen for Marco wasn't Latino enough.
* BystanderSyndrome: Initially, the kids see the Yeerk war as strictly between the Andalites and the Yeerks, which is why Marco is so against getting involved. However, when Jake learns Tom is a Controller, the kids realize that the stakes are much closer to home than previously thought. By the end of the series, the kids have lost their faith in the erstwhile Andalite reinforcements, and have concluded that it's [[AllUpToYou all up to them]].
* CainAndAbel: Tom and Jake, respectively, though in an interesting subversion, [[spoiler:in this case it's the Abel that kills the Cain]].
** That particular subversion appears to be a favorite of K.A's. She also uses it in {{Everworld}}.
* TheCallKnowsWhereYouLive: Marco. Also, Jake and Elfangor.
* CanOnlyMoveTheEyes: Sometimes Controllers can break through the Yeerk's control to portray a meaningful glance or facial expression.
* CantStayNormal: {{Inverted}}. [[spoiler:Cassie is a sub-temporally grounded anomaly, meaning that her involvement/existence will eventually break down any attempt to rework reality, so she can't stay ''abnormal.'']]
-->[[spoiler:"She's a freak," the Drode spat.]]
-->[[spoiler:"Yes," the Ellimist said fondly. "She is."]]
* CasualInterstellarTravel: Averted. There is a [[SubspaceOrHyperspace hyperspace]] analogue called "Zero Space," but its configuration is prone to sudden shifts that may extend what was once a trip of a couple of days into months. [[HyperspaceIsAScaryPlace Among other problems.]]
* CassandraTruth:
** Nobody believes the kids the first time they explain what's going on.
** At one point the Andalites are sending the majority of their reinforcements to the Anati system instead of Earth, believing the majority of the Yeerk fleet to be there. The kids have inside information that the Anati system situation is an ambush (the asteroid fields are rigged with automated turrets and mines). When they hear this, the Andalite command assumes the kids are lying in an effort to become a priority.
* CatchPhrase: Everyone, in narration: "My name is [name.]" Additionally, Rachel's "Let's do it!" and Marco's "This is insane."[=/=]"Are you insane?!" also qualify. Both are frequently {{Lampshaded}}.
** In one instance, the two switched catchphrases, after Rachel goes over their plan:
--->'''''Marco''': That's it exactly.\\
'''Rachel''': Yeah, this is insane.\\
'''Marco''': I know, right? Let's do it!''
** "That was exciting/fun/really cool." "Let's never, ever do it again."
** Ax: "[[TwoOfYourEarthMinutes We have x of your minutes left]]."
*** "They're ''everyone's'' minutes, Ax."
** Jake's "Don't call me Prince." is something between this and a RunningGag.
* TheCavalry: During the fourth book, the Animorphs in dolphin morph save a whale from sharks. Later, they are being chased by the Visser in the morph of an alien sea monster. The whale family shows up and saves them. The exact same thing happens in book 36, oddly enough, also involving whales.
* TheChessmaster: The Ellimist and Crayak.
* TheChainsOfCommanding: A major focus of Jake's personality (combined with ComesGreatResponsibility and IJustWantToBeNormal). Exemplified when Rachel acts as leader for a short while and experiences the same issues, making her wonder whether being leader was the enviable position she once thought it was.
* ChangelingFantasy: Tobias. [[spoiler:Elfangor is his father.]]
* CharacterDevelopment
** The whole series is really about walking the line between this and BreakTheCutie. The humans characters start off the series as five more or less normal kids. By the end, three years later, they are, respectively: a ruthless leader willing to sacrifice anyone at all to win, a bloodthirsty killer who honestly believes that she could not survive in peacetime, a boy who willingly severs all ties with humanity and never looks back, a strategist so obsessed with the "bright, clear line" between himself and victory that he can't turn away from it, and a vicious manipulator who has given up on just about all of her principles. Whether this is character development or character damage is anyone's guess.
* CharacterFocus
* CharacterNameAlias: Marco, Rachel, and Cassie go by: [[TheXFiles Fox Mulder, Dana Scully]], and Cindy Crawford, respectively in #14.
* ChekhovsGunman: In the beginning of ''The Departure'', it's mentioned that a leopard escaped from someone who keeps wild animals. The leopard ends up playing a huge role in the story.
* ChildhoodFriends: Marco and Jake.
* ChildSoldiers: A major focus of the series and a deconstruction of KidHero and WakeUpGoToSchoolSaveTheWorld.
* ChooseYourOwnAdventure: The two Alternamorphs books. The first book cast the reader as a SixthRanger there with the Animorphs at the start, while the second featured the reader as an{{Expy}} of David.
* CityWithNoName: The Animorphs refuse to tell the reader where they live, not wanting the Yeerks to [[LiteraryAgentHypothesis read the books and find them]]. [[WordOfGod According to the author]], she did have a specific location in mind for them, and evidence in the final book (and probably ''Visser'') confirms their location as [[spoiler:somewhere in California]].
* ClusterFBomb / ForeignCussWord: When Erek [[WhatTheHellHero calls Jake out]] in the last book.
* ColorCodedForYourConvenience: Andalite technology tends to be based around the colors blue and white. Yeerk tech (at least that used by Visser Three) is usually black and red.
* ColorMeBlack: Inverted when Cassie, confronted with a racist when travelling back in time, turns herself white - [[{{Animorphism}} into a polar bear]].
* CombatByChampion: The Animorphs vs. the Howlers in book 26.
* ComesGreatResponsibility: Tobias is very serious about this in #1. Jake also notes in [=MM3=] that their power traps them in a bind: they have enough power to fight and make them responsible, but they don't have enough power to actually ''win''.
* ComicBookTime: Played with. Early books in the series had the {{Unreliable Narrator}}s worry about how they would adapt in winter, which implies that their adventures are taking place in Comic Book Time prior to the first winter after receiving their powers. By the end of the series it turns out that ItsAlwaysSpring because of the setting, the worries about winter playing up the LiteraryAgentHypothesis that they could not give away their location, and about three years pass from beginning to end of the series.
* CommanderContrarian: Marco, for two reasons. Firstly, because the kids' plans are usually slapped together at the last second or played by ear and therefore incredibly risky ("This is an ''insane'' plan!"); secondly, because Marco has a talent for zeroing in on inconsistencies, and wants to make the plans as effective and watertight as possible. It's said that pointing out flaws is really all Marco can do, which is what makes him a bad leader, as he's too cautious to actually get anything done. It also makes him the best tactician of the team, as is often pointed out. He couldn't make you go along with it, but he could hammer out a working plan well enough.
* CommonTongue: Gallard is a galactic language designed to be pronounceable by pretty much anyone. It doesn't see much use (although Hork-Bajir occasionally lapse into it) because the primary aliens are the telepathic Andalites and the {{Puppeteer Parasite}}s Yeerks.
* CompetenceZone: Anyone not in the inner circle, though [[JustifiedTrope this makes sense]], as they have the most experience fighting the Yeerks.
* ContestWinnerCameo: Erek King. Actually became a recurring character, and a major player in the final battle.
* ContinuityDrift: In the very first book, it's possible for a human to thought-speak with someone in morph, which is totally ignored in every single other book.
** Due to the fairly large number of these in the series, the [[FanNickname fandom nicknamed]] them [=KASUs=] or "Katherine Applegate Screws Ups[=/=]Screw-Ups" (K.A. [[AscendedMeme herself]] eventually started using the term in interviews) and when the first few books were relaunched in 2011, they were fixed.
** A whole list of [=KASUs=] can be found at this page: [[http://web.archive.org/web/20091027005821/http://geocities.com/sbsa01/kasu.htm "A List of Mistakes in Animorphs"]][[hottip:*:Archive generated by the Internet Archive's Wayback Machine (dating back to October 27, 2009), due to the closure of {{Yahoo}} [=GeoCities=].]].
* ContinuityNod:
** In #54, Ax was promoted from "aristh" straight to "Prince," calling back a conversation between [[TheMinnesotaFats Elfangor]] and Arbron in ''The Andalite Chronicles'', where Arbron snarks that glory-hungry Elfangor's probably fantasizing that they'll make him a Prince without even stopping to make him a full warrior.
** In the last book, when [[spoiler:the ''Rachel'' is about to battle the Blade ship. The ''Rachel'''s weapons can't penetrate the Blade ship's shields, so Jake orders to "Ram the Blade ship". Almost twenty years earlier, Elfangor had issued the exact same command, which won the battle and earned him the rank of War-Prince.]]
** "We're ''not'' morphing ants! We're ''never'' morphing ants again!" or some variant is said every couple books, in reference to one of the kids' earliest missions.
** When Marco morphs lobster to get his keys from the bottom of his pool: "It seemed like a lifetime ago that me and Jake morphed lobsters to escape from the Yeerks by hiding in a grocery store fish tank. The days, man. Those were the days."
** In the penultimate book, Jake [[spoiler:flushes thousands of unhosted Yeerks out of the Pool ship into space.]] This is exactly what [[spoiler:Elfangor refused to do back in ''The Andalite Chronicles'',]] showing that Jake is now far more ruthless than Elfangor was (at least at first).
* ConspicuousCG: You think a book series would be immune to this? Every book features artwork by David B. Mattingly, except the covers done by Romas Kukalis. Most of the first-page illustrations were created by David as either photo manipulations or photo montages. Two, however, stand out. The illustrations for [[http://scholastic.com/animorphs/download/31street.jpg Book 31]] and (to a lesser extent) [[http://scholastic.com/animorphs/download/38hawk.jpg book 38]] use more CG than normal.
* ContrivedCoincidence: The Animorphs contain Ax (Elfangor's brother), Tobias [[spoiler:Elfangor's son]], Marco [[spoiler:the son of Visser One's host]], and Cassie [[spoiler:a sub-temporally grounded anomaly, meaning that her involvement/existence will eventually break down any attempt to rework reality]]. The Drode lampshades this, insisting it ''can't'' be a coincidence, and that the Ellimist stacked the deck.
-->'''Ellimist:'''''(laughing)'' [[MagnificentBastard Did I? If I did, that would be very clever of me.]]
** There are several apparent ones in Book #27, but it is ultimately an aversion. Erik is left unable to move or project his hologram, so the Animorphs carry him out of the mall. There was a major sale, so virtually everyone was elsewhere in the mall and all the cameras are down. They take a bus, and the bus driver doesn't notice. This makes them suspicious. Later, when they realize they will need a sperm whale morph, a sperm whale "happens" to beach itself. This they all realize can't be a coincidence, and that someone is pulling the strings. The Drode turns out to have been behind all of it.
* CoolStarship: The kids themselves are partial to Dome ships, especially newer models like the ''Elfangor''. The ''Rachel'' is also supposed to be pretty sweet.
* CosmopolitanCouncil: The Yeerk Empire is made up of officers called vissers, who take orders from the Council of Thirteen.
* CorneredRattlesnake: [[spoiler:David]].
* CoveredInMud: At one point, Cassie jokes about how Rachel never seems to get dirty - that any mud just seems to be deflected away. She throws a ball of mud at Rachel, who knocks it away without it splattering all over her. Cassie comments that Rachel's hand probably isn't even muddy, but Rachel refuses to show her.
* CreateYourOwnVillain: David, arguably. He was pretty obviously already not a nice guy, but some of the things Jake and the others did [[WhatTheHellHero really didn't help]].
* CreatorProvincialism: It's not really made clear what's going on outside the States during the entirety of the war. We know that at least one major head of state outside the U.S. is a Controller (the President of the U.S. isn't though), but except for, like, four missions outside the country, the kids mostly ignore everything beyond U.S. borders. Or more than a day's journey from their home town, for that matter.
* TheCretaceousIsAlwaysDoomed: In ''Megamorphs 2: In the Time of the Dinosaurs'', a hole in space-time causes the Animorphs to accidentally arrive one day before the asteroid hit. They get into a tussle with several warring AncientAstronauts trying to colonize Earth, the losing species attempting revenge by diverting the path of a passing comet. The meteor's strike creates another hole that lets the kids return to the present. It was one of the weirder books.
* CrypticallyUnhelpfulAnswer:
-->Tobias: <No one wants to ask you because they think maybe it's rude. But everyone wants to know how you eat with no mouth.>
--> Ax: <How do I eat? Well, I have hooves, don't I?>
** (It's later revealed that Andalites absorb nutrients from grass through their hooves.)
* CurbStompBattle: Erek King, the millennia-old robot that is capable of generating personal forcefields and shrugging off being hit by a truck. He can move faster than the eye can follow and is described as being able to "obliterate you down to your individual molecules"; however, he's hardwired to hate violence and can never commit any violent act. In one instance, this is subverted, allowing him to rescue the Animorphs. The fight lasted less than a minute, and was [[GoryDiscretionShot only vaguely described]]. In the time it took you to read this paragraph Erek managed to kill dozens of Hork-Bajir. Afterwards, Erek ''begged'' to have his original protocols restored. [[BloodKnight Rachel]] saw it and the brutality ''reduced her to tears.''
* {{Cult}}: The Sharing
* CulturalPosturing: Ax does this frequently.
* DaddyHadAGoodReasonForAbandoningYou: .....because he was actually an alien warrior and there was some time travel involved.... Sorry, [[spoiler: Tobias.]]
* DangerousDeserter: David in #22 ''The Solution''.
* DarkAndTroubledPast: Marco. The disappearance of his mother and the subsequent split of his family caused him to become more cynical and, in effect, more ruthless and pragmatic and less attached to romantic, idealistic principles.
* DeadManWriting: Aldrea's stored persona.
* DeadpanSnarker: Marco, usually, but Rachel and Tobias are both pretty sarcastic when the situation calls for it.
* DeadPersonImpersonation: David [[spoiler:morphing Jake and Rachel's dead cousin]].
* {{Deconstruction}}: In spades. Really, the whole angle of the series.
** KidHero: It's obvious from the get-go that the kids, having no sort of military knowledge or practical connections whatsoever, are pretty much just making it up as they go and doing the best they can with what they have, and they're closer to ChildSoldiers than anything else.
** WakeUpGoToSchoolSaveTheWorld: As you'd expect, fighting as an uncover guerrilla resistance agent tends to take up a lot of the kids' spare time and energy, and is too important to leave to an extra-curricular schedule. The war takes place at the expense of the kids' personal lives (sometimes forcing them to fight for up to, it is mentioned, three days straight without sleep) and their grades and sociability are pretty much done for by the end of the series.
** TheGoodGuysAlwaysWin: Not a full deconstruction, as [[spoiler:the kids actually do manage to save their home planet]], but the fact that they're massively outgunned is a major element in the story, and the kids comment from time to time that only rarely are their missions actually successful. One of the major messages of the series is that, despite idealistic platitudes, victory ultimately goes to those who are ruthless and desperate enough to take the most extreme measures, not to the morally superior.
** JusticeWillPrevail: Most of the series' villains never get their comeuppance - the Blade ship escapes and Esplin 9466 is never executed. K.A. Applegate has stated that this is meant to reflect real wars, where people are rarely held accountable for the evil they commit.
*** Not everyone would agree that execution is justice.
** ViolenceIsTheOnlyOption: Initially, what with this being an invasion and occupation, the kids consider armed resistance to be their only option. But it quickly becomes apparent that Yeerks are NotSoDifferent from the Animorphs themselves, capable of being reasoned and negotiated with, and at times a pacifistic and diplomatic solutions work out.
** WhatMeasureIsANonHuman: Hork-Bajir, Taxxons and Yeerks are pretty fucking scary aliens to look at, and the kids initially assume them all to be evil monsters. However, by the end of the series, it's obvious that despite outward differences, the three species actually have much more in common with humankind than is apparent at first glance.
* DestructiveSaviour:
** Throughout the whole series, Jake and the kids wait for Andalite reinforcements to save them from the Yeerk invasion; originally, Elfangor had promised them that they would have to fight for no more than a year. This year eventually stretches into ''three'', as Andalites see humans as a low priority and take their time getting there. Unfortunately, by the time the Andalites arrive, [[spoiler:they've realized they've made a huge mistake: the Yeerk presence on Earth is ''much'' larger than anticipated (in the rare instances where the kids made contact with Andalites, the Andalites assumed they were lying to become a top priority). By that time, the secret war has erupted into a full-blown conflict, so the Andalites decide to wait for the Yeerks to completely commit their forces planetside. Once that happens, they will "quarantine" Earth: A nice way of saying that they're going to completely sterilize Earth from orbit to kill everything, Yeerk military and humans alike.]]
** When the Yeerks invade the Hork-Bajir planet, [[spoiler:the Andalites send only minimal reinforcements. When it's made clear that the Yeerks are winning, Alloran creates a quantum virus that will kill every Hork-Bajir on the planet, in order to make sure that a minimum number of Hork-Bajir can be used as hosts.]]
** Eventually averted in the last book. Prior to the last book, Ax notes that [[spoiler:the prolonged war against the Yeerks has given the Andalite military command more power than they rightly should have, and they no longer properly represent the will of the people as they're supposed to]]. This comes to be proven true in the last book, when [[spoiler:Ax invokes his legal right to challenge the decision of Andalite Captain-Prince Asculan regarding Jake's promise to Yeerk prisoners on Earth, by which Ax's challenge would be tried before a civil court as opposed to a military one. It is heavily implied that the civil government and the people are surprisingly supportive of the human victory; Prince Asculan is forced to consult with his political advisors, and, realizing that he doesn't stand much of a chance in a civil trial, Asculan begrudgingly bows to Jake's wishes]].
* DeathFromAbove:
** In the second-last book, Visser One kills [[spoiler:the Auxiliary Animorphs and some of General Doubleday's troops]] by shooting the Pool ship's Dracon cannon from orbit.
** [[BigBadassBirdOfPrey Tobias]] whenever he's feeling hungry.
*** Or in battle. ''TSEEEEEER!''
* DeathIsCheap:
** [[spoiler:Marco gets brought back to life twice. Although in one instance, he's not technically dead, just comatose, because he's in cockroach morph, which is practically unkillable.]]
** In ''Elfangor's Secret'' it's known that one of the kids will have to die to set things right, [[spoiler:and Jake is shot in the head as they cross the Delaware. But because Visser Four's host is {retgone}d, there was no reason for them to travel through time in the first place and Jake pops back, alive. In addition, because Jake is dead and the Ellimist said only one Animorph would have to die, the rest of the Animorphs are invincible for the rest of the book, even when they should by all means be dead.]]
* DerelictGraveyard: The Nartec city.
* DescendingCeiling: Used by Visser Three to scare the Rachels in #32 because he thinks she's an Andalite and Andalites are somewhat claustrophobic.
* DespairEventHorizon: [[spoiler: Jake's parents' infestation. And then it gets even worse when Rachel and Tom die.]]
* DeusAngstMachina: Pick a character, any character. Especially the auxiliary Animorphs. And, in a weird way, Loren.
* DeusExMachina: To the Leeran conflict, the Animorphs could be considered this. They are not supposed to be there, show up right when all hope seems lost, and happen to have the exact abilities needed to ensure Andalite victory there.
* [[DevilsAdvocate Devil's Advocate]]: Marco would sometimes offer the Devil's Advocate view on missions.
* [[spoiler:DidNotDieThatWay]]: Marco believed that his had mom died in a boating accident, [[spoiler:but it was a cover so the Yeerks could get her away without a lot of questions]].
* DidYouJustFlipOffCthulhu: Jake to Crayak, repeatedly. One time, the rest of the team to Crayak by [[spoiler:bringing Jake back to life]].
* DiminishingVillainThreat: Visser Three. He's completely immoral and monstrous, but as a consequence of appearing in almost every book and not killing the Animorphs, he quickly starts to come across as a blundering clod. Visser One even acknowledges this in the Visser Chronicles, comparing him less-than-favorably to [[AlienScrappy the Helmacrons.]] While he does get promoted to Visser One towards the end, he still doesn't undo a lot of this.
** It becomes funny when even Visser Three starts noticing the effect. "Would it be too much to ask for one of you to actually HIT SOMETHING?!?!"
* DisabilitySuperpower: Literally. Most of the Auxiliaries are hospitalized children, as Yeerks are less likely to infest the disabled. It's mentioned that they have a much easier time controlling the instincts of a new morph, as their minds are stronger from spending so much of their lives unable to move their bodies as freely.
* DivineChessboard: The heroes are guided by BigGood The Ellimist, while BiggerBad Crayak is behind the Yeerks and other adversaries.
* TheDarkSideWillMakeYouForget: Affects all the kids to some degree. Rachel in particular, as can't remember what she was like before the war started.
* DisposableSuperheroMaker: {{Subverted}} when [[spoiler:the morphing cube turns out to have survived the destruction of Elfangor's ship]].
* TheDogBitesBack: [[spoiler:Tom's Yeerk.]] Guess Visser Three should have promoted him when he had the chance.
* DoNotGoGentle: [[spoiler:Rachel.]]
* DontYouDarePityMe: Marco hates being pitied by the others, and often shoos Cassie away when she tries to play therapist. Jake, similarly, can't stand pity, because he feels that as the leader, he should appear flawless and confident in every decision he makes, and therefore tries never to let the others see him second-guessing himself.
* DoomedHometown: [[spoiler:Bug fighters destroy the kids' hometown in the second last book to create a giant dead zone around the Pool ship's landing site. They reduce the entire city to a desert of ash, so the nothing can get close without being seen.]]
* DoubleConsciousness: The Morphing technology grants you your animal form's instincts as well as your own consciousness. Sometimes these play well together, sometimes not. It usually depends on how humanlike said animal is. Tobias struggled with this while in ShapeshifterModeLock in some early books, then came to terms with it.
** The kids wonder about the morality of morphing, as controlling the animal's natural mind is similar to what Yeerks do to humans and the kids decide early on to never morph sapient species without the permission of the person. [[spoiler:Near the end of the series, some missions become impossible to accomplish without morphing human or Hork-Bajir, so the kids compromise their morals. By the end of the series morphing Hork-Bajir is commonplace and Tobias uses it as a battle morph.]]
* TheDragAlong: Marco initially, though he eventually grows out of it.
* DragonInChief : Visser Three
* DramaPreservingHandicap: Initially, it's in both sides' best interest to keep the war a secret. The Yeerks prefer a strategy of infiltration, then suddenly seizing control of the planet, in order to minimize both Yeerk casualties and the deaths of thousands of potential host bodies. The Animorphs, on the other hand, prefer the war also remain a secret, for tactical reasons: the Yeerks have much more advanced technology and would certainly win any open engagement where they were free to use all of their weapons (a bunch of animals can't do much good against Yeerk capital ships destroying cities from orbit). Also, the primary reason the Yeerks want Earth is because of the large population, and a war would reduce the value. On the other hand, there are so many damn humans compared to Yeerks (6 billion versus a couple hundred thousand) that open warfare might even hurt the Yeerks despite their serious technology because humanity could and probably would ZergRush any terrestrial fortifications, at least enough to turn the campaign into a PyrrhicVictory that the Andalites could take advantage of.
* DreamSue: When Jake becomes a Controller early on, one way the Yeerk tortures him is by replaying an embarrassing fantasy of Jake's from years prior, where he won the big basketball game with a difficult shot and was then congratulated by Tom (a much better basketball player).
* DreamingTheTruth: [[spoiler:It turns out #41 was all a mind exercise, during which Jake rediscovers the things they're fighting for in the first place.]]
* DrivesLikeCrazy:
** It's a running gag that whenever Marco drives any vehicle, he sucks at it. In one instance Marco achieves this with an ''Abrams tank''.
** It's later revealed that Tobias is an even worse driver; Marco even calls him on it.
* DropInCharacter: Erek was good at walking up from out of nowhere. So was Mr. King. It's a Chee thing.
* DumbBlonde: Subverted. Everyone outside the group assumes Rachel to be a ditzy airhead. [[BloodKnight Nothing could be further from the truth.]]
** Not to mention she's a really hot teenager, so boys make [[ReallyGetsAround hasty assumptions]]. They get corrected really, really fast.
* DyingAsYourself: A host will sometimes experience a moment of freedom before death as the Yeerk will abandon them in an attempt to save themselves.
[[/folder]]

[[folder:E-H]]
* EarlyInstallmentWeirdness: The first ten books have a disproportionately large number of [[FanNickname KASU]]s and introduce a lot of plot points that are never mentioned again, such as Hork-Bajir having a biological imperative to make war with each other every sixty or so years (later books indicate Hork-Bajir don't even ''live that long'') and the warning that Yeerks have infiltrated the Andalite home world, which never goes anywhere.
* EarnYourHappyEnding: After years of unimaginable pressure and WarIsHell torment, the kids become the greatest heroes in the history of humanity. However, only [[spoiler:Marco, Cassie and Ax get to profit from it - Jake's clinically depressed due to his actions aboard the Pool ship, and Tobias struggles to live a solitary existence in the woods]].
** And [[spoiler:Rachel, who died in the final battle]].
*** And, of course, thanks to the [[spoiler:budding ''Kelbrid'' war and Ax's kidnapping, life turns out pretty shittily for everyone]].
**** Well, except [[spoiler:Cassie]].
* EitherWorldDominationOrSomethingAboutBananas: Ax does something like this once when the kids are in fly morph:
--> '''Ax''': He’s welcoming the visser back aboard the Blade ship. Or he may be telling him his brother is a meteor fragment. I understand Galard, but this morph’s hearing is very uncertain.
* EldritchAbomination:
** Crayak.
** The Drode to some extent.
* ElectricInstantGratification: Worked into an ElectricTorture device, and proves more effective on hawks than standard torture. A hawk can handle ''torture'' just fine; animals are good with dealing with pain. But a hawk doesn't know what to do with that kind of pleasure, and lowers its defenses for when the torture comes back.
* ElevatorFloorAnnouncement: Marco parodies this at one point.
* EnemyCivilWar: Visser Three and Visser One's rivalry creates a fragile equilibrium that the heroes take advantage of. [[spoiler:It ends in Book 45, with Visser One's execution.]]
* EnemyMine:
** Perhaps the most important one is the above-mentioned rivalry between Vissers Three and One. Visser One is just as bent on world domination as Visser Three is, but she and the Animorphs agree that things would be worse for all of them if Visser Three overthrew her, at least for the time being.
** In Book 24, the Animorphs attempt to convince the Helmacrons to take out Visser Three for them, but the Helmacrons turn out to be so annoying they agree to a temporary truce with Visser Three just to get rid of them.
** In ''Elfangor's Secret'', the Ellimist and Crayak both agree that the Time Matrix should not be in the hands of a mere mortal and help the Animorphs stop Visser Four.
** In the last few books, they team up with [[spoiler:Tom and his followers]] in order to hijack the Pool Ship. [[spoiler:Both sides then double-cross each other, but the Animorphs end up winning in the end.]]
* EngineeredPublicConfession: Or rather, an engineered public demonstration. In Book #35, after spending days harassing a particular famous-but-psychologically unstable Controller, Marco ([[MisterMuffykins as a poodle]]) provokes the Controller into attempting to strangle him to death on national TV.
* TheEternalChurchill: The Animorphs choose fight over flight often, even if it seems hopeless. Maybe especially if it seems hopeless. The fact that humans do this mystifies Visser Three. Visser One recognizes that makes humans very dangerous.
* ETGaveUsWiFi: In ''The Andalite Chronicles'' it's implied that Elfangor made friends with Bill Gates and Steve Jobs, which led to the advancement of human technology. Also played with in #45 ''The Revelation'', when it's revealed that the Yeerks helped humans discover Zero-space. Lampshaded by Ax in the same book.
* EvenEvilHasStandards: A good deal of the series' ambiguity revolves around the differing custums and ethical values of humans, Andalites and Yeerks which make it very difficult to draw the line between moral and immoral warfare.
-->'''Jake''': He's a prisoner of war. We don't kill prisoners.\\
'''Visser One''': No. Of course not. You merely blow up ground-based Yeerk pools and kill thousands. And then another seventeen thousand of our brothers here on this ship. Defenseless, harmless, unhosted Yeerks. Murdered. But you don't kill prisoners.
* EvenEvilHasLovedOnes:
** Visser One (not [[spoiler:Eva]], the actual Yeerk) and her [[spoiler:human children]], who were, oddly enough, allowed to remain uninfested during their time with her.
** [[SixthRanger David]]'s main motivation is to free his parents from Yeerk control, but since he doesn't know about starving out Yeerks, he tries to make a deal with them instead. [[spoiler:Once that's off the table, he tailspins ''real'' fast.]]
** In ''The Alien'', a minor Yeerk agrees to help Ax assassinate Visser Three in revenge for the Visser allowing his lover to die of Kandrona starvation.
* EverythingsEvenWorseWithSharks: And Controller sharks, well, that's just ''awful''.
* EverythingsSquishierWithCephalopods: In ''The Exposed''.
* EveryoneCanSeeIt: Despite initial trying to keep their relationship low-key, it was very apparent to everyone that Jake and Cassie were smitten with each other. Marco also sarcastically makes the same observation in an early novel when Rachel pulled a HeIsNotMyBoyfriend regarding Tobias.
--> '''Rachel (threateningly):''' What did you say?
--> '''Marco's thoughts:''' ''Like it was some big secret.''
* EveryoneCallsHimBarkeep: The Ellimist. Oddly, Ellimist was originally his ''online gaming handle,'' which he adopted as his name when he ascended to omnipotence. His real name is Toomin.
** And the Drode. According to the... er, being himself, it means "[[{{Trickster}} wild card]]."
* EveryoneMeetsEveryone: Partially subverted. Each of the five main characters knew, or at least knew of, the other four before the series began, but they weren't close.
* EveryoneLovesBlondes: Rachel appears to be just a pretty face as she is tall, graceful, blond haired, blue eyed, and glamorous but her fearlessness makes her more than that.
* EvilGloating: A couple times in minor books, but most notably done by [[spoiler:Tom's Yeerk in the final two books (narrated from different perspectives):]]
-->[[spoiler:"You appear to be experiencing some engine trouble, Visser," Tom said, gloating.\\
<TheEmpire will track you down and kill you for this, you do understand that, I hope?> Visser One said.\\
"Oh, I doubt it," Tom said cheerfully. "The Andalite fleet is rather close by. It's possible that I misled you on that point." He was all but giggling.]]
* EvilIsHammy: '''Visser Three'''.
--> "[[ThisCannotBe You dare defy me! You dare resist!]]"
* EvilOverlord: Visser Three. The first Visser One might also qualify, as things she does are undeniably ruthlessly evil, but they're more motivated by her military goals than an inherently malicious personality.
* EvilerThanThou: The whole hierarchy of the Yeerk Empire, but particularly the Visser One/Visser Three rivalry.
* EvilMeScaresMe: Rachel gets this several times- when she gets split in half; when she gets turned into a monster; when she gazes into the abyss of her soul and sees a fearsome BloodKnight staring back at her.
* ExactTimeToFailure: Ax has to give regular time reports so that the Animorphs [[ShapeshifterModeLock don't exceed two hours in morph]].
* ExposedExtraterrestrials: Pretty much all the aliens, particularly the Andalites, who first thought that human clothing was part of human's bodies. Ax has trouble understanding why he has to wear clothing while morphed as a human.
* ExtrudedBookProduct: Roughly the entire second half of the series was ghostwritten, although KAA was still involved in coming up with the plot outlines.
* FakingTheDead: More than once. [[spoiler:Visser One sets it up so that it looks like Eva, Marco's mother, drowned at sea, so that she had an excuse for disappearing into space. Later, Marco has Erek and Mr. King stand in for himself and his father when the Yeerks come to kill them. Finally, Jake fakes the deaths of ''all'' the other Animorphs in order to sneak them on the Pool ship in his final BatmanGambit.]]
* FallenHero: [[spoiler:Jake]].
* FamilyUnfriendlyViolence / FamilyUnfriendlyDeath: The fight scenes in this series are quite graphic. Ripping out throats, hacking off limbs, stabbing, shooting, maiming, disemboweling - you name it, someone's done it.
** What makes the violence notable is that because morphing heals every wound the Animorphs have, the same character can have the same limb hacked off ''multiple times''.
* FamousLastWords:
** "JAKE, STOP HER!" [[spoiler:Tom, right before Rachel kills him.]]
** "I love you." [[spoiler:Rachel, to Tobias.]]
** "Do the right thing." [[spoiler:David, to Rachel.]]
* FanNickname: Emohawk for Tobias. Hawkward for Rachel/Tobias moments. KASU for "Katherine Applegate Screws Up[=/=]Screw-Ups", or the mistakes between books by the author and her ghostwriters.
* FantasticRacism: In addition to the commonly dismissive perspective the Andalites take to the Yeerks, the series gets some good mileage out of Tobias's attitude towards other birds. He calls Golden Eagles "nuts" (they occasionally hunt hawks) and is generally disdainful of seagulls and pigeons. There's even a debate as to whether or not this could count as racism by the other Animorphs.
* FantasticSlurs: Yeerks are "slugs", Andalites are "grass-eaters", Taxxons are "bugs" or more commonly "worms", Hork-Bajir are [[SarcasmMode "geniuses"]] and "bark-chewers", and humans are "monkeys."
** The standard Yeerk-on-Andalite insult seems to be "Andalite filth!," while the inverse is "Yeerk scum!"
* FantasticVoyage: In book #42, the Helmacrons take Marco hostage by invading his body. The Animorphs shrink down and go in after them.
* FasterThanLightTravel: By means of Zero-space (Z-space for short), which is "anti-space." It shifts and reconfigures, meaning the time it takes to travel from one planet to another isn't consistent. Z-space is also [[ShapeshifterBaggage where the Animorphs' excess mass goes]] when they morph creatures smaller than they are (as mass can't be created or destroyed), and, presumably, where they derive the mass for when they morph larger creatures.
** This also makes travel through Z-space dangerous, as that excess mass ''is'' physically present and can be crashed into.
* FateWorseThanDeath: [[spoiler:David]]. Ironically, [[spoiler:Cassie chose to permanently [[ShapeshifterModeLock trap him as a rat]] specifically because she felt it was better than killing him]].
* FictionalCounterpart: WAA (Web Access America) = AOL, Jeremy Jason [=McCole=] = Jonathan Taylor Thomas, ''Power House'' = ''HomeImprovement''.
** John Berryman (Visser Four) isn't ''quite'' a FictionalCounterpart of John Barrymore, but he ''was'' a Shakespearean actor, though not a very good one.
* FightingFromTheInside
* FinalBattle: A pretty epic one, too, although the main characters don't directly participate in it. (Jake even describes it as the "final battle.")
* FinalSpeech: ''Hirac delest'' is an Andalite term for one's last thoughts or [[FamousLastWords final words]]. It is a fairly common practice among Andalite warriors to record it just before their demise. ''The Andalite Chronicles'' takes this concept UpToEleven, as the ''entire text'' actually serves as Elfangor-Sirinial-Shamtul's ''hirac delest.''
* FireForgedFriends: How the Animorphs became friends. Before the meeting with Elfangor, they weren't close - Marco and Jake were best friends, Cassie and Rachel were best friends, but Rachel and Jake weren't close cousins, Cassie and Jake only barely knew each other, and Rachel and Marco only knew of each other. Nobody knew or liked Tobias much, and, of course, they had never met Ax. But as Marco notes, after someone saves your life a couple times, you tend to cut them a little slack.
* FirstNameBasis: Most of the main characters. Out of the seven main Animorphs, only Jake and Ax's full names are ever revealed. ''The Pretender'' and ''The Andalite Chronicles'' hint that [[spoiler:Tobias' last name is [[LukeIAmYourFather Fangor]]]], but it's never confirmed. See NoNameGiven below for more on that.
* FirstEpisodeSpoiler: Tobias is [[spoiler: [[ShapeshifterModeLock trapped in the body of hawk]]]] and Jake's [[spoiler: brother Tom is a Controller.]]
* FiveManBand: It's pretty much unanimous that they ARE a five man band, and that Jake is TheHero and Rachel is TheBigGuy, and it's generally agreed that Marco is TheLancer. But good luck getting people to agree on where Cassie, Tobias and Ax fall in the dynamic. See also TheChick, above, [[http://tvtropes.org/pmwiki/remarks.php?trope=Literature.Animorphs and the Animorphs Discussion page]].
* FiveTokenBand: Jake and Rachel are Jewish, at least on their fathers' sides, Cassie is black, Marco is half-Hispanic, Tobias comes from a ''very'' broken home, and Ax is an alien.
** Technically, as far as the religious "authority", so to speak, is concerned, Jake and Rachel are almost certainly NOT Jewish - their father is, but in Judaism only the mother's religion matters (as for whether you are Jewish or not). We never hear specifically that their mothers aren't Jewish, but it seems to be implied from the way they specifically single out their father (instead of saying "parents"). So while they may be ''practicing'' Judaism (which they are evidently not), only the most liberal of reform Jews would consider them ones.
* {{Flanderization}}: Rachel, though it was intentional.
** All the characters were Flanderized, actually, to a lesser extent. Cassie was the most notable (other than Rachel) - she goes from a slightly more moral person than the others to someone who ''couldn't stand to kill Visser 3''. Note that her Flanderization was mostly reversed after book 45.
** Jake was noticabley Flanderized as well - his leader angst goes from mild to extreme, until the last book, at which point [[spoiler: he feels like Tom and Rachel's death was his fault and becomes clinically depressed.]]
** The Flanderization was, really, the point. The war took whatever aspect of their personalities was most useful to the fight (bloodlust, strategizing, manipulating people, etc.) and forced them to exaggerate it until it ate the rest of their lives.
* FlashbackNightmare: Often, but mentioned more than seen.
* FloorboardFailure: In ''The Reaction'', Rachel involuntarily morphs an elephant on the second floor of her house, causing the floor to collapse.
* FlowersForAlgernonSyndrome: Tobias' ShapeshifterModeLock and morphing ability. Poor lil' [[FanNickname Emohawk]] can't catch a break.
* {{Foil}}: All over the goddamn place. All the main characters act as foils to each other to some extent.
** Marco is foil to Jake (taking orders vs. giving orders), Tobias (pragmatism vs. idealism), Cassie (pragmatism vs. moral relativism) and Rachel (subtlety vs. brute force).
** Jake is foil to Marco (taking orders vs. giving orders), Rachel (leadership vs. insubordination; they say this is what happens when two "strong" personalities mix), Tobias (confidence vs. insecurity) and Ax (leadership vs. loyalty to authority figures).
** Cassie is foil to Marco (pragmatism vs. moral relativism) and Rachel (peace vs. conflict).
** Tobias is foil to Rachel (peace vs. conflict), Jake (confidence vs. insecurity), and Marco (pragmatism vs. honor).
** Rachel is foil to Marco (subtlety vs. brute force), Jake (leadership vs. insubordination), Cassie (peace vs. conflict), Tobias (peace vs. conflict) and Ax (giving orders vs. taking orders).
** Ax is foil to Jake (giving orders vs. taking orders), Marco (pragmatism vs. "warrior ethics"), and Rachel (emotionality vs. logic).
** Ellimist and Crayak act as foils to each other (life vs. death, the forces of good vs. the forces of evil).
** Visser Three is foil to Visser One (psychopathic, sadistic, irrational evil vs. pragmatic, intelligent, everyday evil).
* FootFocus: As morphing results in lost or destroyed shoes, the Animorphs are frequently barefoot. Every book mentions this fact and sometimes describes what the characters are feeling underneath their feet as they go about their adventures.
* ForegoneConclusion: All of the ''Chronicles'' books, to some extent, by way of being stories told in flashbacks about established characters.
** ''The Andalite Chronicles'' is narrated by Elfangor, who died in the first book. His commanding officer is Alloran, the host body of Visser Three. Even if you didn't know either of these things before reading, the FramingDevice is Elfangor transmitting his last testament telepathically to his ship minutes before he dies, and he mentions being responsible for creating the Abomination, Visser Three.
** ''The Hork Bajir Chronicles'' is about the invasion of the Hork Bajir homeworld by the Yeerks. At the start of the series proper, all of the Hork Bajir are enslaved by Yeerks.
** ''Visser'' is about Visser One giving testimony about her invasion of Earth while on trial for treason. It is obvious from the series proper how successful she was.
** ''The Ellimist Chronicles'' is the Ellimist telling a dying [[spoiler:Rachel]] how he became the godlike being the main characters know him as.
* {{Foreshadowing}}: In ''The Underground'':
-->'''Rachel (narrating):''' But even I have enough sense to know the words "we have to win" are the first four steps on the road to hell.
** ''The Ellimist Chronicles'' begins and ends with the Ellimist visiting a dying Animorph. He admits that he did not cause him/her to be an Animorph, and that it was random chance. According to ''Megamorphs 4'', this means that this can only be [[spoiler: Jake or Rachel. It turns out to be Rachel]].
** Most of the information about Z-Space's finer workings comes from the books narrated by Marco. [[spoiler:Marco's Dad is the first human to discover the existence of Z-Space and build a transmitter.]]
* ForWantOfANail: The cause-and-effect domino line in this series is staggering. Remember, while the kids' part of the story only lasts three years, the entire conflict lasts over two decades, with the kids only jumping in near the end. Much of what happens earlier in the war only has a real effect on the story as the war reaches its conclusion. What if the Skrit Na had never kidnapped Loren and Chapman? No Animorphs, no war on Earth period. What if Arbron hadn't been trapped as a Taxxon? Earth would've been successfully taken over by Yeerks.
** And my personal favourite: What if a pubescent Jake had felt the need to act macho to impress his crush Cassie? ''Planetwide Andalite genocide and enslavement and an unstoppable Yeerk Empire.''
** But then, this entire trope is justified; [[AWizardDidIt an Ellimist did it]].
* ForgotICouldFly: Sometimes they forget the different abilities their morphs have.
** There is something of a RunningGag with them forgetting that cockroaches can fly. Subverted once, where narrator remembers that cockroaches can fly and attempts to do so, only to remember that cockroaches can't fly well.
** There's also a rather infamous incident in ''The Familiar'' where Future Cassie is thrown from a tower. Jake has to choose between saving her and saving the world, apparently because she's forgotten she can ''morph''.
* FourStarBadass: General Doubleday.
** Though, as Jake notes, his rank isn't very intimidating to any of the Animorphs; "After you've stared down the likes of Ellimist and Crayak, you don't quiver just because some guy has stars on his shoulder."
* FramingDevice: All of the ''Chronicles'' books. ''The Andalite Chronicles'' is presented as Elfangor's last testament (known by Andalites as a ''hirac delest''), given in the final moments of his life. ''The Hork-Bajir Chronicles'' is told to Tobias by Jara Hamee sometime between books 13 and 23. ''Visser'' has, by far, the most in-depth one, switching back and forth between Visser One's memories and her present-day trial. Finally, ''The Ellimist Chronicles'' is narrated to a then-unnamed dying Animorph, indicating that at least one of them will be die.
* FreakLabAccident: How the Ellimist became a godlike being. Having his consciousness spread across multiple advanced bodies, some remaining in space and some in Z-space while the rest was sucked into a black hole, allowed his consciousness to integrate with the fabric of the universe. However, he notes that while the odds of this happening once were [[MillionToOneChance astronomical]], the fact that it happened meant that Crayak could replicate it.
* FriendToAllLivingThings:
** Cassie. To the point where, as a Yeerk incredulously discovers, she feels guilty about killing a ''termite queen''.
** The Pemalites were biologically designed to be a PlanetOfHats for this trope.
* FrickinLaserBeams
* AFriendInNeed
* FutureBadass: Jake in ''The Familiar'' again.
** "A body a Yeerk would give three ranks for."
** Future Tobias also qualifies. Future Cassie is a weird subversion.
* GambitPileup: In Book #53 The Answer, [[spoiler: Jake uses the auxiliary Animorphs, and the U.S. National Guard to distract Visser Three, so he can sneak above the Pool Ship. Or so Visser Three thinks. Actually, Jake is relying on him to believe that, so he doesn't realize that Jake and the other Animorphs are '''already''' aboard the ship, with help from Tom, who wants Visser Three dead himself, and plan on fighting him with the help of the free Taxxons. '''But''', Tom decides to betray Jake to Visser Three at the last moment, which Jake saw coming and avoided dying with help from the Chee, who Tom and Visser Three didn't even know existed.]] Yeah.
* GambitRoulette: [[spoiler:Cassie's surrender of the blue box.]]
* GenderBender: Pretty much all of the kids at some point: Rachel's eagle, acquired between books 1 and 2, is male, as is the grizzly bear that she acquired in book 7. Marco acquires a girl wolf in book 3, while Jake, Marco and Ax all become a female skunk in book 9, and Rachel and Cassie (along with the four boys) acquire a male polar bear in book 25. The only human example, however, is Tobias, who acquires Taylor, a human female, in book 43.
* GeneralRipper: Alloran. Elfangor is ''really'' surprised when he finds out he [[spoiler: UsedToBeASweetKid.]]
* GeneticMemory: Howlers, though [[spoiler:their memory is constantly tampered with by Crayak, to preserve their naiveté and maintain their usefulness as [[AlwaysChaoticEvil killing machines]]]]. Andalites also possess a genetic memory, though it's much more random and is only triggered as a near-death-experience; [[spoiler:Tobias]] gains it after [[spoiler:acquiring his uncle, Ax's, DNA]].
* GenreSavvy: Marco shows a strong indication that he knows he's in a fairly dark series with a rather sadistic author whenever he's being a DeadpanSnarker.
--> Cassie: "I wonder if there's a limit to how many morphs you can do."
--> Marco: "I guess we'll find out. Probably at the worst possible time."
*** Later in the same book, upon being told they're not comic book heroes, he makes the rather prophetic comment: "Yes, but I really really want it to be a comic book. See in a comic book the heroes don't get killed."
--> Marco: Now I have a new superstition. Anytime I'm not worried, I worry.
--> Marco: I'm paranoid, sure. But that doesn't mean I don't have enemies.
* GlamourFailure: [[spoiler: A Yeerk controlling Jake gets surprised and glares at Ax (Yeerks and Andalites are practically bloodsworn enemies). The reaction warns the Animorphs that something is wrong. The Yeerk does an okay job protesting his innocence until Ax moves to acquire Jake's DNA so he can play his role while the Animorphs make sure Jake isn't infested. As soon as Ax comes in contact with Jake's skin, the Yeerk yells out, "Get your hands off of me, you Andalite filth!" thus torching any chance he had of solving the situation with his secrecy intact.]]
** Other than that, one of the [[ParanoiaFuel really disturbing things]] about this series is that, for the most part, there ''is'' no GlamourFailure on the part of the Yeerks; their replacement and impersonation of their host is so thorough and effective that even their closest friends and family never notice the difference. There is a subtle change, though: Marco notes in an early book that "Tom just hasn't been acting like Tom" after the kids realize Jake's brother is a Controller. Similarly, Melissa notices that her parents, who are Contollers, always seem insincere. The Yeerks essentially rely on the fact that no human would automatically assume that a subtle change in personality would mean an alien parasite in their head.
*** Near the end of the series, there's a lot more GlamourFailure in the series. For example, Tom will disappear for hours without giving an explanation. In one instance he mutters to Jake about how he's "preparing" for something. Justified in that by the end the Yeerks have amassed enough power to forget stealth and secrets, and are simply waiting for the orders for an open war.
* GodForADay: Rachel was given the chance to become the ultimate fighting machine by Crayak. However such things are not much fun for a BloodKnight and it leaves only the satisfaction of sadistically snuffing out your enemies which is a road she doesn't feel comfortably going down when Crayak starting saying she is NotSoDifferent.
* GodwinsLawOfTimeTravel: Subversion: Visser Four rockets through the time stream, altering the results of battle to see to it that the human race is more cowed and easier to enslave. The book opens in a totalitarian alternate present with slavery still legal and women who "don't know their place" in reeducation camps, but no actual Nazis. During his travels he goes to D-Day to ensure a Nazi victory, but [[spoiler:thanks to his previous changes, there never were any Nazis.]]
** [[spoiler: But they do see Hitler. Though tempted, nobody does anything to him since ''this'' Hitler is just a scared guy driving a jeep. Then Tobias's Hork-Bajir blade either slips or "slips." The question of which it was kinda hangs there unstated.]]
* GogglesDoSomethingUnusual: During the David Trilogy, the Animorphs try to infiltrate the Marriot resort as seagulls, but a Human-Controller wearing sunglasses is able to stun them and other birds with his sunglasses from a distance.
* GoOutWithASmile: [[spoiler:Rachel]], in the final book.
* GoingNative: [[spoiler:Elfangor]] in ''The Andalite Chronicles''. Also [[spoiler:Arbron]] in the same, [[spoiler:Aldrea]] in ''The Hork-Bajir Chronicles,'' [[spoiler:Toomin]] in ''The Ellimist Chronicles'' [[spoiler:with the Andalite cavemen]] and [[spoiler:Essam]] and, to a degree, [[spoiler:Edriss]] in ''Visser.'' Those Chronicles books certainly did follow a formula, didn't they?
** Also, Ax, to a degree. By the end of the series he's arguably more human than Andalite in terms of personality and habits.
** This applies to the Chee as well after they used their holograms to disguise as humans.
* GoodAllAlong: Yeerks, like humans, aren't all evil. While most Yeerks, such as Visser Three, genuinely are evil and support the imperialist philosophy, some Yeerks are part of a Yeerk Peace Movement dedicated to the creation of artificial, non-conscious host bodies ([[spoiler:In an alternate future, the Yeerk Peace Movement becomes the Evolutionist Front, a splinter-cell terrorist group, albeit with similar goals as the YPM.]]) Even more startling: Some of the Yeerks who inhabit host bodies are ''children'', who are given the choice between participation or execution.
** It's implied that even the imperialist Yeerks are only like that because they've been spoon-fed Empire propaganda since birth. As Cassie puts it: "They don't know any better. If you were raised since birth on Empire propaganda, you'd fight to take over Earth, too."
*** Not to mention their natural form is very much AndIMustScream. If the only way for you to see, taste, build, basically be anything more than a ''slug'' was to take over a sentient being that could do those things, well...many humans would not be strong enough to pass that up either.
** Taxxons are actually intelligent creatures who posses an unfortunate evolutionary trait: They're constantly hungry. When they see an open wound they go insane with hunger, "it's like watching sharks react to blood in the water." Because of this, the Taxxons have been pressed into bondage by the Yeerks, who feed them.
*** Not even "pressed into" bondage; they ''willingly'' offered themselves to the Yeerks as hosts in hopes that the Yeerks would be able to suppress their insane hunger. ''It didn't work.''
* GoodRepublicEvilEmpire: Played with a bit, as the Yeerks are clearly an empire and the Andalites a kind of republic, but the vast majority of Andalite government and military leaders the characters meet aren't much better than the Yeerks.
** Oddly, while the Yeerk Emperor is chosen for life by the Council of Thirteen, the Council itself is democratically elected; meanwhile, the Andalite government is practically a junta; specifically, the Andalite civil government is apparently democratic, but it is implied that, over the decades-long Yeerk War, their military has (intentionally or unintentionally) usurped a large degree of informal autonomy.
* GoodThingYouCanHeal: Morphing heals injuries, meaning Applegate abuses the hell out of this trope. It becomes an issue when they enlist disabled kids as backup, and those who had merely been permanently injured get healed and now have to hide their returned mobility.
* GrayingMorality: One of the major themes of the series. It starts out as BlackAndWhiteMorality, but ''The Departure'' turns the black into grey as we learn more about the Yeerks (though with Visser Three in charge, a very dark grey ) and ''The Hork-Bajir Chronicles'' turns the white into gray as we learn more about the Andalites.
* GrailInTheGarbage: The Animorphs first meet David when they discover that he's selling the Morphing Cube online without having any idea what he's got his hands on.
* GrandFinale: The final two books.
* GRatedDrug: Instant maple and ginger oatmeal is addictive to Yeerks, replaces part of their brain stem, eliminates their need for Kandrona rays, and drives them insane.
* GrayingMorality: It starts off as a typical children's sci-fi with the Yeerks as evil and the Animorphs, and by extension the Andalites, as the good guys. This doesn't stick.
* GreyAndGrayMorality
* TheGreys: The Skrit Na, who like to abduct people and perform bizarre medical experiments on them for no discernible reason. The other characters note this but don't spend a lot of time trying to figure it out.
* GrowingUpSucks: Especially when you're trapped in an interstellar war to save human freedom at age thirteen.
* GroinAttack: Rachel does this to a male Controller once, and Loren does this to Chapman in the Andalite Chronicles.
* HandshakeRefusal: At the end of the episode where Tom and Jake are taken to the country for their grandfather's funeral longer than the Yeerk can survive, the Animorphs save the day by breaking Tom's leg so [[StatusQuoIsGod he gets sent back into town]]. Marco, who came up with the idea, offers his hand to Jake as a sign of all being forgiven (Jake had been dealing with the possibility that his brother might be finally freed), but Jake just lets it sit there.
* HealingFactor: One of the perks of the morphing power. As long as you can survive the injury long enough to morph or demorph, you're golden. And since the morphs are based on DNA, not the physical condition of the target, a person can acquire a morph of an injured (though it still has to be living) animal and turn into it at full health. [[spoiler:Several of the Auxillary Animorphs and Loren were crippled as a result of injury, not birth defects, so they were back in full health upon their first morph]].
** The Hork-Bajir can heal extreme wounds very fast, such as when Dak Hammee cuts his own head open, shows his brain to the Animorphs, and is able to close the wound simply by pressing the two sides of his cut flesh together. It's not like he isn't hurt from it, but it was clear that the injury was far from lethal, and a scar forms over the cut in moments.
* {{Hammerspace}}: Zero-space.
* HannibalLecture: Tobias uses this while Taylor is torturing him.
* HappyPlace: When Taylor figures out that simply torturing Tobias won't work, she starts sending him to his HappyPlace too, attempting to shatter his mind by jumping from pure pleasure to pure pain. [[spoiler:It works, but Taylor is too far gone herself to notice.]]
** Although interestingly enough, you could also argue that she tries this method specifically because Tobias is sending HIMSELF to a HappyPlace (albeit not a terribly happy one) in order to keep from breaking down. Up until that point, he'd been surviving Taylor's methods by hiding in the hawk half of his mind, which, being the brain of a wild animal, was much better at living with pain without suffering deep psychological damage than his human side was. That's why the HappyPlace method was so effective- the hawk brain was good at dealing with pain, but it didn't know what to do with happiness, which isn't something that a hawk brain understands. The happiness was just too tempting for Tobias' human side, and it drew it out of hiding- at which point Taylor slammed down on the pain button again and wacky fun ensued.
* HealingFactor: Morphing regenerates injuries, making the Animorphs and other morphers very, ''very'' hard to kill.
* HeelRealization: Rachel has one after she threatens to kill David's parents.
* HeKnowsTooMuch: Not advocated, but suggested, when the group talks about David. It makes everyone very uncomfortable.
* HeroicBSOD: Many, many; particularly Cassie in "The Departure" and Jake in "The Ultimate" and "The Beginning".
* [[spoiler:TheHeroDies: Rachel.]]
* HeroicVow: Two major ones. Firstly, the kids will never morph a sentient species without the individual's express permission. The other vow is a little more vague: The kids "fight Yeerks, but won't become them". This essentially means the kids agree to not use the same underhanded tactics Yeerks use (cold-blooded murder, ganging up on a single enemy, et cetera); this is so that the kids can try to maintain their morality while fighting a guerilla war in which they are hopelessly outgunned.
** [[spoiler:The kids wind up breaking both of these vows.]]
* HeroicSacrifice: Tobias counts for this one right from the very first book, The Invasion. During the battle under the school, he chooses to attack one of the Hork-Bajir ready to infect Cassie with a Yeerk. This in turn leads to him ultimately being trapped as a Red-tailed Hawk, permanently. He gets better, though. Sorta. Although the characters begin to wonder if it was intentional.
** [[spoiler:Rachel]].
* HeterosexualLifePartners: Gafinilan and Mertil if you care to read it that way. Briefly Marco and Ax, arguably, after [[spoiler:Marco fakes his death]].
** Jake and Marco.
** Also Tobias and Ax, with Ax even referring to the Andalite name for this trope (shorm).
* HeWhoFightsMonsters: Some of them were ''seriously'' at risk of slipping into this as the war ended.
** [[spoiler:And Rachel ''did'' slip into it. Before her final mission, she accepts the fact that she's become something of a nutcase and thinks that Jake's made the right decision in using her appropriately.]]
* HeyItsThatGuy: MelindaMetz, writer of RoswellHigh (which was the inspiration for the TV show {{Roswell}}), was the ghostwriter for ''The Sickness'' and ''The Prophecy''.
* HeyThatsMyLine: Rachel's reaction whenever somebody else says, "Let's do it."
* HiddenDepths: In the final story arc, [[spoiler:Jake relinquishes command for a short period. When he becomes leader again, he's an absolute authority figure, and refuses to second-guess himself or let anyone else question his decisions, working from the standpoint that "a leader who shows weakness invites disaster". This ultimately leads him to becoming the most ruthless character in the series.]]
* HistoricalInJoke: Erek was FDR's butler and coined the phrase "New Deal" in a card game. He also worked on the Pyramids and did Catherine the Great's hair. Elfangor also talks about his human friends "Bill" and "Steve" and their primitive ideas regarding computers.
** Also, Mr. King was the one who suggested heat to Pasteur as a means to kill bacteria. Also, remember that painting of Washington crossing the Delaware? The kids go back in time and find out the river and the night were freezing. So not only did the kids see first-hand that Washington never posed like that, they directly state that if he posed like that in the middle of the night on the front of a boat crossing an ice-cold river, his soldiers would have thought he was a loon.
* HitlersTimeTravelExemptionAct: Visser Four actually ''hoped'' to find Hitler and warn him of the Allied invasion on D-Day. Trouble is, [[spoiler:thanks to the other ways he screwed up time, the Nazis are a combined French and German force, the invaders are all British, and Hitler is a Jeep driver, and as Marco points out, the "Nazis" don't actually appear to be Nazis anymore, and they can't even be sure the French/German alliance is the "bad guy"]]. So rather than being of assistance, Visser Four is captured and imprisoned.
* HiveMind: Howlers. And Taxxons, through The Hive. Taxxons can voluntarily cut themselves off from The Hive, though, and they do when the Yeerks arrive.
* HoldingBackThePhlebotinum: The instant maple and ginger flavored oatmeal is only referenced in ''one book''. In their defense, as Jake points out, battles that involve oatmeal will never really end up being historical.
** Also, if Erek King could fight, the war would be over in about a week. Unfortunately, while he recognizes the necessity of the kids' cause, he himself finds violence to be too horrific to participate in (largely because his memories of the experience ''never'' fade) and is programmed to never commit any violent act.
** ''Everyone'' is severely traumatized by seeing Erek fight and kill, even Marco, who's unconscious for most of that battle.
*** The carnage is so intense that it leaves ''[[BloodKnight Rachel]]'' a weeping, semi-broken-down wreck.
** It's also implied that this Cassie was left traumatized by this as well and that it was a major factor in her decision to [[spoiler: temporarily step down]] nine books later.
* HonorBeforeReason: The ordinarily-pragmatic Jake's approach to David in the David Trilogy is very much this, most likely to facilitate David's [[spoiler:impending FaceHeelTurn]].
* HopelessWar: The Animorphs' objective isn't to win, but to at worst slow down the Yeerk invasion before the eventual loss and at best to slow down the invasion until the Andalite reinforcements arrive.
* HoldingOutForAHero: While they try to slow the invasion on their own, the kids spend the better part of the series waiting for Andalite rescue. And waiting. And waiting. And waiting...
* HorrorHunger: The Taxxons.
* HotMom: Eva.
* HourOfPower: The 2-hour time limit.
* HufflepuffHouse: The Yeerk Peace Movement, anything in the Anati system, the Rakkam Garroo conflict, the free Hork-Bajir.
* HughMann: Played straight with Ax, who, in human morph early on, is just [[UncannyValley not quite right]], thanks to a cocktail of misunderstanding human humor, taking directions too literally, and [[SenseFreak having access to taste buds]]. By the last third of the series, he's become much better at passing for human.
** Completely averted by the Yeerks, as human-Controllers play their parts perfectly 99% of the time.
* {{Hulkspeak}}: The Hork-Bajir.
* HumansKillWantonly: Ax becomes disgusted with humans during Megamorphs #3, when he sees the nature of human wars. He claims that though the Andalites had their own wars, they were never as pointless or sadistic as human wars were. He also claims that Andalites never deliberately killed children or committed genocide to other Andalites.
* HumansAreSpecial: Both serious and not-so-serious examples. A prime example is the Yeerk designation of humanity as a "Class Five" host. They are intelligent and numerous but at the time of discovery possessed few natural or technological defenses against Yeerk infestation. They failed to count on human adaptability, though...
** One notable example is Ax's observation that the Animorphs are using the morphing technology in ways the Andalites never even considered, in weaponizing it and acquiring dozens of different morphs for different situations, especially in so short a time. Most Andalites use it for subterfuge, and tend to specialize, only acquiring one or two animals over the course of their entire lives.
*** That's not all there is to his observations, either. In the very first book from his point of view he noted that humanity went from basic powered flight to moon landings in a quarter of the time it took Andalites.
** The sheer length of series entry on that page should say something about how much this trope plays a part in the series.
** The first Visser One in the series had this to say:
---> "Humans have fought thousands of wars. Thousands! We as a race have fought a mere handful. They run straight into the bullets, Visser Three, again and again. Did you know that? They attack against insane odds. They defend what can’t be defended. Outnumbered, outgunned, surrounded, hopeless, they will still fight, fight, fight till they are each and every one dead. Something you might know if you stopped posturing long enough to learn something!" [[hottip:*: of course she then gives Marco the opposite speech later.]]
* HumanityEnsues:
** Ax, by combining DNA from all the kids, makes his own human morph. He's weird.
** Also, an ant morphs Cassie. The results is so horrific that even ''Cassie'' thinks it should be euthanised. In the same book, a buffalo morphs Chapman; as buffalo have a sense of individuality and more intelligence than an ant, this doesn't go over ''quite'' as poorly.
* HumansThroughAlienEyes: Ax, Elfangor. And in ''Visser,'' Visser One.
* HumiliationConga: [[spoiler:David]], after spending his entire arc being a self-centered JerkAss. He thinks he's pulling one on [[spoiler:Rachel]] but he's really being lined up for a FateWorseThanDeath.
** Also [[spoiler:Visser One, in a way. You get the sense that his whole defeat is very humiliating for him; especially the fact that even after losing his enemies won't just kill him and get it over with. Visser One first abandons his host body then has to go through a war crimes trial, which Jake describes as "very un-Yeerkish".]]
* HumorlessAliens: Andalites don't seem to understand the human sense of humor or its purpose, though Ax gets better at is as the series progresses.
* HundredPercentAdorationRating: [[spoiler: All the Animorphs after the war, but Jake becomes a legendary figure verging on superhuman.]]
* HurtingHero: All of them.
* HyperspaceIsAScaryPlace: The kids are, in one, instance, "pulled" into zero-space while in morph; that is, their consciousness was pulled into their extruded mass left in zero-space. Zero Space is - not pretty.
[[/folder]]

[[folder:I-L]]
* IAlwaysWantedToSayThat: Rachel and "ItWasADarkAndStormyNight."
** Marco and "Let's do it," Rachel's catchphrase. He just wanted to say it ''first.''
** Jake and "''Charge!''"
** In an interview, Creator/KAApplegate stated that Rachel's "Dark and stormy night" and "I always wanted to write that" lines were Applegate speaking to the readers.
* IAteWhat: Sort of. Ax eats all kinds of stuff (cigarette butts, engine oil and a paper plate to name a few) but it doesn't really bother him. He can't see what the others are getting so upset about.
--> '''Cassie:''' Were the nachos good?
--> '''Ax:''' They tasted of grease and salt. Plus, there was another flavor that reminds me of some delicious engine oil I tried once. Oil. Oil-luh.
--> '''Jake:''' Ax...You know how I mentioned you can't eat cigarette butts or dryer lint? Add engine oil to the list.
* IdentityImpersonator: In later books, the Chee start doing this for the kids when they have to go on long missions.
* IdiosyncraticEpisodeNaming: The regular series books are all in the form of "The <Noun>." Likewise, the three prequel books are all in form of "The <Species of the Person the Book Focuses On> Chronicles."
* IfIWantedYouDead: The second-last book. Not only could Tom have fought them with his battle morph (jaguar), but he could've conceivably called in every Hork-Bajir-Controller on the planet and taken them down.
* IfYouDieICallYourStuff
* IfYouKillHimYouWillBeJustLikeHim: [[spoiler:When the war ends, Jake refuses to kill Visser One. Tobias, enraged, demands to know why, claiming that Visser One was the one responsible for the entire war. Jake replies quietly that they "don't kill prisoners."]]
** [[spoiler:The Visser immediately mocks his hypocrisy; Jake has just killed seventeen thousand unarmed, helpless Yeerks. Not to mention he and the others had blown up the shopping mall to take out the Yeerk pool beneath it, which killed thousands of unhosted Yeerks and hundreds of innocent people.]]
** [[spoiler:Rachel is about to kill Tobias' captor Taylor, but Tobias urges her: "Be Rachel. Not her."]]
* IJustWantToBeNormal: During the war, pretty much everyone except Rachel.
* IKnowYouAreInThereSomewhereFight: Rachel tries to talk Tobias into controlling his Deinonychus morph, first by appealing to his humanity. But when that doesn't work, she grudgingly tries to accept the fact that he's a bird now.
* IKnowMortalKombat: Marco tries to use knowledge from video games to drive a truck and operate a ''tank''. He doesn't kill anyone (trash cans excepted), but he does scar them for life.
* {{Immortality}}:
** CompleteImmortality: The Ellimist and Crayak.
** ImmortalityInducer: During their adventure back in time (MM3), Jake (and the others, after his death).
* ImpactSilhouette: In book #25, ''The Extreme'', the Animorphs (as Polar Bears) are being chased by Venber at the Arctic Yeerk base. Marco stops quickly and a Venber misses him, slamming through a steel door and making a vague Venber-shaped hole in it. Marco even calls it a "Bugs-Bunny-runs-through-the-door kind of hole."
* ImperialStormtrooperMarksmanshipAcademy: Visser Three: "Would it be asking too much for one of you to actually ''hit'' something?!!"
** Justified in that most of the Yeerk Laser weapons were developed for Hork-Bajir use and humans find them unwieldy to aim and use.
** And to be fair, they hit more often than most "Stormtroopers" they just never get a kill.
* ImportedAlienPhlebotinum: The Escafil Device, which transfers the morphing power.
* ImpostorExposingTest: In ''The Unexpected'', Cassie, hiding from the Yeerks on an airplane, tries to pose as a passenger. The Yeerks, knowing she's the only one on the plane who hasn't been affected by their paralysis-inducing phlebotinum, ferret her out by shooting everyone with low-intensity Dracon beams and seeing who flinches.
* IncredibleShrinkingMan: Happened twice. Both involved the Helmacrons.
* InformedJudaism: Jake and Rachel are presumed Jewish (most of their parents and siblings have Hebrew names, and Rachel flat-out states "My dad's Jewish," when they visit D-Day. Dialogue from #21 and #31 allow us to conclude that their dads are brothers.), but nothing of their beliefs or holidays is mentioned beyond that.
** Well, according to Ax, Jake's family says a short prayer before dinner, but we don't know which one.
* InHarmsWay: Rachel. Also everyone else besides Cassie to a lesser extent.
* InsaneAdmiral: Yeerk Vissers in general. Visser Two from ''The Deception'' is utterly ''bat-shit crazy'', and gets bonus points for taking over an actual admiral.
* InsectoidAliens: The Taxxons.
* TheInternetIsForPorn: Actual pornography is implied once or twice, but this being a kids' book, we get a more toned-down version: Marco uses the internet almost exclusively to look up scantily clad girls.
* InterspeciesRomance: Aldrea and Dak Hamee, Elfangor and Loren. Also, Tobias and Rachel, sort of (Tobias is stuck as a hawk, but he was originally a human and thus identifies as one. [[spoiler:Also, while his original form is ''genetically'' fully human, his father was actually an Andalite in human morph, so it might be vaguely interspecies even if he wasn't a hawk most of the time.]])
* ImNotDoingThatAgain: Frequently used as a catchphrase, but once very serious, when the kids morph ants - the ant morph has some ''very'' disturbing side effects.
** Cassie also says this when she leaves the Animorphs for a brief period, referring to a particularly grisly battle.
** Ax also drops this one in #31, after torturing Chapman.
--->< I will gladly fight this Controller, and even, in fair battle, kill him, but I am not a torturer. >
* InnocentAliens: Subverted in a variety of ways. Much like AlwaysChaoticEvil, even the good guys have their flaws.
** Andalites are the "good guys" and Ax often points out the immorality of human actions for Aesop effect - for instance, he states that human wars are often pointless and needlessly cruel. However, setting aside the horrifying ruthlessness of the Andalite military, Andalite citizens themselves are no saints. They have a variety of distasteful flaws, such as extreme arrogance. Most notably, they intensely hate ''vecols'' - the disabled, who, they believe, should ostracize themselves from society to preserve themselves from the shame of being "incomplete" and therefore worthless. Most notably seen when Ax strongly objected to meeting Mertil, the marooned Andalite fighter pilot from #40, The Other, and Mertil's companion Gafinilan opposed the other Animorphs meeting him as well, on the grounds that subjecting Mertil to the public eye would be shameful.
** Hork-Bajir ''used'' to be a species of InnocentAliens. It wasn't that they were pacifist - they simply didn't understand the concept of fighting. The Yeerk-Hork-Bajir war, however, changed that. Hork-Bajir are still simple pacifists in nature, but they're far from the InnocentAliens they used to be.
** Also, [[spoiler:the Howlers, who are, from a certain standpoint, the most innocent species that the kids meet. Unfortunately, for Howlers, "fun" means "killing the shit out of everything they see." Howlers are a species of genetically engineered killing machines. It's just that they don't know that killing is wrong, and Crayak preserves their naivete by altering their collective memory]].
** The Pemalites may fit this trope, though the kids never meet the Pemalites themselves, as they were killed by the Howlers thousands of years ago.
** And the mind-reading giant frogs, the Leerans.
* ItsAllMyFault: Jake, concerning every single thing that goes wrong.
* ItsPersonal: David and Rachel.
* ItsUpToYou: Combines with ComesGreatResponsibility. The kids are the only ones who know about the invasion who also have the power to resist it. If the kids give up, Earth is doomed. This doesn't make them happy.
* JerkAss: Marco and David, though Marco's generally regarded as more likable about it.
* KangarooCourt: Visser One is tried as a traitor and an Andalite sympathizer, but in actuality, Visser Three set up the whole thing and convinced the Council to go through with it in order to usurp her position.
* KickedUpstairs: Tom's second Yeerk, who is improbably promoted to chief of security despite being the ''last'' Yeerk qualified for the position. It's implied that he's promoted simply because the job requires working closely with Visser Three, which GenreSavvy Yeerks recognize immediately as a death sentence.
* KickTheDog: Literally. To keep alleged FriendToAllLivingThings William Roger Tennant from recruiting for the Sharing, Marco morphs his stepmother's annoying poodle and torments Tennant every minute possible, with the namesake result televised live.
* KillThePoor: One of the Megamorphs books begins in an alternate universe where the homeless "are rounded up and shot."
* KindRestraints: The team has to tie up Jake when he's accidentally infested, to starve out the Yeerk in his head, and they have to constantly watch him on top of it, because they know the Yeerk will try to morph to free him from the restraints.
* KnightOfCerebus: While the series was never particularly lighthearted, the events of the David Trilogy really ushered in the WarIsHell era, forcing the heroes to take extreme measures to attain victory.
* KnowNothingKnowItAll: Rachel's mother Naomi, who doesn't adapt well to going from high powered attorney to camping with aliens and subordinate to her teenage nephew.
** Not at first, but Naomi eventually proves herself rather useful, helping the Hork-Bajir draw up their own Constitution and persuading [[ReasonableAuthorityFigure Captain Olston]] to lend his support to the team.
* KnowWhenToFoldEm: [[spoiler:At the end of the final battle. After it becomes clear that Tom plans to kill Visser One using his own personal Blade ship, the visser essentially surrenders to the kids once they arrive on the bridge.]]
** [[spoiler:Similarly, once the Controllers onboard the Pool ship realize what has happened, they surrender to the kids in exchange for amnesty and a chance to acquire the morphing power (to permanently morph animals and move away from parasitism). The surrendered Yeerks got off quite well, all things considered.]]
** In ''The Capture'' this is revealed to be a major tenet of Yeerk psychology: Yeerks will give up when the odds don't favor them rather that fight against impossible odds as humans do. This semi-defeatist mindset is presented to explain away the BondVillainStupidity of Jake's Yeerk, but later books are consistent with this, as it comes up again in VISSER and ''The Answer''.
* LampshadeHanging: Generally, tropes in this series are lampshaded if they aren't deconstructed or subverted (though a couple are played straight).
* LaResistance: Twice, actually. The premise of the series is one, the final arc is the second.
* LargeHam: '''Marco.''' Especially during any of the few [[BreatherEpisode Breather Novels]].
** Forget Marco, [[EvilIsHammy Visser Three]]. The number of times he goes for the SoftspokenSadist approach can be counted on one hand ([[BadBoss the one he just chopped off]]).
* LaserGuidedAmnesia: Rachel in ''The Andalite's Gift''.
** Averted with [[spoiler:Tobias's mother, Loren.]]
* LastNameBasis: Chapman. In the main series, he's the main characters' assistant principal, so it's rather understandable that they refer to him by his last name, with or without a Mr. In ''The Andalite Chronicles'', however, he reveals that his first name is Hedrick, but he prefers to be called Chapman, anyway.
* LeftHanging:
** The reader never finds out who burned down Joe Bob Fenestre's house. For that matter, we never find out what happened to Joe Bob Fenestre at all.
** Did Rachel [[spoiler:kill David]]?
** In #41, the whole BadFuture thing turns out to be a mind exercise brought on by some other entity that is studying humans. It's not Ellimist or Crayak... So who was it?
** The ending of the whole series, actually…more or less.
* LesCollaborateurs: Some members of The Sharing. In an alternate timeline where the kids didn't meet Elfangor, ''Tobias'' became one, albeit because The Sharing was able to appeal to his lack of friends.
* LightFeminineAndDarkFeminine: Cassie and Rachel respectively have shades of this.
** Funnily, not to be confused with their inverted skin tones.
** Also, possibly Rachel in ''The Separation'', when she literally splits into two different people after her starfish morph goes wrong. One is timid, caring, gentle, and pacifistic; the other is dark, ruthless, and obsessive.
* LightningBruiser: Many of the kids use LightningBruiser-esque animals as their battle morphs. Jake's tiger and David's lion are the most obvious examples, but Rachel's bear and Marco's gorilla can also motor when they have to, while remaining very, very, strong.
* LikeParentLikeSpouse: Tobias's mother Loren is a feisty, fearless, often reckless and smartmouthed blonde who falls for a guy outside her species.... hmm, I wonder who that sounds like.
* {{Lilliputians}}: The Helmacrons (though they might fit better under LilliputianWarriors).
* LimbSensationFascination:
** Ax, and Andalites as whole, do not have mouths and if they morph into a creature with one then the feeling of taste drives them mad. Every time Ax turns human his friends have to stop him from devouring everything from cinnamons buns to cigarette butts.
** Yeerks naturally are blind slugs, and possession of their victims is intoxicating because of all the new senses they gain. Even Visser Three, the Yeerk DragonInChief, fell in love with the sense of sight.
* LineInTheSand: Literally. After the Yeerks find out where the Hork-Bajir valley is located, they plan to storm it and kill everyone. Jake and his friends attempt to explain to Toby that going into battle is suicidal, and to demonstrate his point Jake draws a line in the sand and asks the Hork-Bajir to vote on which course of action is the smartest. Jake's point backfires when every Hork-Bajir votes to fight back.
* LiteralSurveillanceBug: The Animorphs use insect morphs to spy often.
* LiteraryAgentHypothesis: Mentioned at the start of every book, but it gets weird because [[spoiler:Rachel continues to narrate immediately after her death.]]
* LivingWithTheVillain: Jake's brother was a Controller.
* LoadsAndLoadsOfCharacters: Let's see: Jake, Marco, Cassie, Rachel, Ax, Tobias, David, Tom, Eva, Peter, Loren, Naomi, Jordan, Sara, Chapman, Erek, Visser Three, Visser One, Toby, Jara Hamee, Mr. King... And none of those are one-shot characters, either.
* LongRunningBookSeries
* LosingTheTeamSpirit: The group breaks up for various reasons once or twice. And near the end of the series there's a period where they all fucking hate each other.
* LukeIAmYourFather: Twice. [[spoiler: Marco's mother]] has been taken over by the leader of the invaders. [[spoiler: Tobias' father]] was the war hero alien who gave them their powers. Justified late in the series; the Drode whines that [[spoiler:the Ellimist stacked the deck to get Marco and Tobias, along with Ax and Cassie, into the Animorphs]].
[[/folder]]

[[folder:M-P]]
* MacGuffin: Several over the course of the series, including the Pemalite crystal, the blue box, the Anti-Morphing Ray, and the Pemalite ship -- but the ultimate MacGuffin is the Time Matrix, which was the catalyst to the Andalites and Yeerks even ''discovering'' Earth, let alone the war itself.
* MadScientistsBeautifulDaughter: Estrid.
* MadeOfIron: Because the kids can morph or demorph to heal all bodily injuries, it takes a lot to kill them. Typical battles include at least minor injuries. More commonly the kids suffer major injuries; arms being cut off, major blood loss, et cetera. The most memorable example was in the second last book, when Jake, woozy from blood loss, gets shot in the head by a human-Controller. Miraculously he survives long enough to demorph.
** Bear-Rachel getting an arm cut off and using it as a weapon also qualifies as memorable.
** Possibly Lampshaded or Didn't Do the Research. In the first book, after morphing Homer the golden lab, Homer-Jake identifies the "other dog" AKA real Homer "was neutered, just like him." The cloned DNA wouldn't have carried over the neutering process' result.
*** Applegate rectifies her mistake later in the series. When Ax morphs a neutered bull, the kids expect him to be docile. But because he absorbed unaltered DNA, Ax is very temperamental. The kids figure out why, so the dog thing could possibly be chalked up to an UnreliableNarrator, who, uh, didn't really know what a neutered dog looked like? Okay, so it doesn't make much sense, but she corrected her mistake is what I'm saying.
** Also, after reassuming the original form, the morpher's bodily injuries could theoretically be healed. In Megamorphs 2, Tobias says that he should be able to heal his broken wing after morphing and demorphing. Ergo, any bodily injury sustained in the original form of the morpher should be repaired, including brain damage, amputation and the like. Age would remain unaffected as DNA degrades with age: a newborn cloned from a 27-year-old's cells will essentially start with 27-year-old DNA and cells.
*** James, the leader of the Auxiliary Animorphs, is crippled due to an accident rather than a genetic disease, so after demorphing from pidgeon he finds that he can walk again. Similarly, Loren's blindness is cured by morphing. Marco also heals a dog bite by morphing then demorphing.
* MagicFromTechnology: Morphing in a nutshell, although it follows MagicAIsMagicA.
* MagicPants: Lampshaded very early on.
* TheMagnificent:
** A complete list of Jake's nicknames: Big Jake, Fearless Leader, Jake the Mighty, Prince Jake, Jake the Yeerk-Killer (sometimes Big Jake the Yeerk-Killer, used mockingly), Jake the Ellimist's Tool, and (in the alternate timeline from Megamorphs #3) Supreme Leader.
** And, of course, Marco's always calling Rachel "[[XenaWarriorPrincess Xena: Warrior Princess]]".
** Esplin 9466 the Abomination.
** The Beast Elfangor.
** After the war, it's Aximili "of Earth".
* MamaBear: Both Loren and Eva qualify, but Naomi, for all her bossiness, thickheadedness and inflexibility, is the epitome of Mama Bear. In one instance, she attacks a grizzly bear that she thinks poses a threat to her daughters Jordan and Sara with a ''spice rack'', and knowing her, probably would've won if it weren't for the fact that the bear was her eldest child.
** As another troper noted elsewhere on the site, badassery is genetic in the ''{{Animorphs}}'' universe. Rachel's a MamaBear to the rest of the kids, and Jake is the PapaWolf.
* ManipulativeBastard: Cassie, Marco, David, The Drode. But most of all, Jake, who becomes more and more manipulative as the series progresses.
* MauveShirt: Most of the named "auxiliary Animorphs".
* MeaningfulName: Sometimes obvious, sometimes not. According to WordOfGod, LordOfTheRings references are everywhere; Yeerk is a reference to "Yrch", the Elvish word for Orc, and Elfangor's and Aximili's names are references to elvish cities.
* MetaGuy: Marco. The others often do it, but Marco makes it an art form.
* MercyKill: Used disturbingly.
* MiddleManagementMook: Chapman.
* MildlyMilitary: The Animorphs themselves. Not at first, but as the war goes on and they get a sense of discipline, they definitely grow into this.
* MilitaryBrat:
** David.
** Jake kind of fits this. Neither of his parents are military, but his great-grandfather served in World War II and ''The Resistance'' is written from the POV of his ancestor who served in the Civil War.
* MillionToOneChance: At some point the reader may sit back and think, "Hey, wait a second. Yeerks are a race with insanely superior weapons. Not only that, but anyone can be a Controller. And this is a worldwide invasion. The heroes are six teenagers who live in a small town in California that can turn into animals? How can they stop the invasion? A bunch of animals couldn't beat the U.S. Army, never mind the Yeerks." This is lampshaded many, many times throughout the series, as the kids admit that at best all they do is slow down the Yeerks from time to time. They mostly lose battles and they agree that they'll never really be able to beat the Yeerks. They ''do'' eventually win, due in large part to the morphing technology being so dangerous and versatile. Rachel sums it up pretty well [[spoiler: during David's betrayal]] when the kids are reflecting on how hard it is to kill an Animorph:
-->'''Rachel''': Just us. Just us against an enemy that could become any living thing. An enemy that could be anywhere, at any time. An owl in a tree, a spider in your house, a cat in the night, and then... Then, when you were unprepared, when you were vulnerable, a lion or a tiger or a bear[[hottip:*:Oh, my!]].\\
I was starting to see why Visser Three hated us so much.
* TheMindIsAPlaythingOfTheBody: Morphs come complete with the animal's instincts and desires. Some are useful, some can be ignored, some (ant, Taxxon) are horrifying.
* TheMinnesotaFats: Elfangor, but only from Ax's perspective. In fact, the main reason the Animorphs go to rescue Ax is because they feel an obligation to any Andalite because of Elfangor's kindness. From his own perspective, Elfangor is more of a NiceJobBreakingItHero.
* MisterMuffykins: Euclid, Marco's stepmother's evil poodle.
* MixAndMatchMan: Ax's human form.
* {{Mordor}}: The Yeerks' home planet. Also, in a way, the Yeerk pool.
* MookPromotion: [[spoiler:Tom, who becomes an important antagonist late in the series, and a major player in the final battle.]]
* MoreThanMindControl: There are voluntary Controllers, people who willingly let a Yeerk infest them. Many of them are simply so alone, so desperate to be part of ''something'', that they're willing to give up their free will. The Sharing's main purpose is to find these sort of people and indoctrinate them.
* MultipleNarrativeModes: They're primarily written in the first person, but switch into the third person at one point.
* MundaneUtility: Includes getting keys off the pool floor and getting into concerts for free. Jake ''tries'' to forbid this, but he keeps failing miserably... especially when he wanted to go to both concerts.
* MyGodWhatHaveIDone: After the war, Jake is so guilty about [[spoiler:ordering to have the Yeerk pool flushed into space]] and [[spoiler:sending Rachel, his cousin, to kill Tom, his brother (the former dies in the process)]] that he is driven to clinical depression. As Marco puts it: [[spoiler: "He wore Rachel and Tom and those seventeen thousand Yeerks around his neck like the [[Literature/TheRimeOfTheAncientMariner Ancient Mariner and his albatross]] ... He could've snapped his fingers and had anything he wanted, but he didn't ''want'' anything. Except for Rachel and Tom to be alive. For Tobias to come back. To unlive that fateful order that doomed seventeen thousand Yeerks."]]
** The whole series exemplifies this, to some extent. The kids agree that self-defense is justified, but the problem is when you kill a Controller, you don't just kill the Yeerk; you're also killing the host, who is completely aware but unable to stop the Yeerk. The kids debate during the entire series what is acceptable when it comes to self-preservation and exactly how far is too far. Initially the kids take a very narrowminded, black-and-white view - "We have the right to do anything we have to to win" - but as they mature and experience more in the war their moral lines become blurred to the point that they don't know the difference between right and wrong.
* MyGreatestFailure: Jake, whenever he recalls the David incident. Also the fact that Jake couldn't save Tobias from being trapped as a hawk.
** Even moreso, the fact that he couldn't save [[spoiler:Rachel]] or [[spoiler:Tom]] from dying, not to mention the [[spoiler:order to kill seventeen thousand Yeerks]]. Those two failures become to the entire focus of his personality for about five years.
* MythologyGag: [[spoiler: Jake's decision to [[RammingAlwaysWorks "ram the Blade Ship"]] in the series' ending mirrors Elfangor's decision to ram an enemy ship in ''The Andalite Chronicles''. While Elfangor won his battle involving that tactic, the result of Jake's decision is [[BolivianArmyEnding unclear]].]]
* NamesToRunAwayFromReallyFast:
** “The Abomination” is a name given to Esplin 9466 after he infests the Andalite Alloran. Granted, he fights with a sledgehammer, but do you really want to piss off someone with a sledgehammer of monstrous morphs from dozen of systems?
** And from the Yeerks’ perspective, Jake is "Jake the Yeerk-Killer", and he earns the title.
** Ax is kind of amused when he learns that Yeerks refer to his brother as "Beast Elfangor."
* TheNapoleon: The Helmacrons.
* NarrativeProfanityFilter: Being teenagers, and this being a very realistic series, the kids swear and flip each other off a lot. Depending on the "explicitness" of the word, it may or may not be directly written. "Crap", "damn" and "hell" are okay. Nothing else is explicitly mentioned, though the reader can guess the exact word most of the time.
* NatureIsNotNice: A major theme of ''The Secret''.
* NecessarilyEvil: A lot of what the kids do. It causes them problems.
* NeverFoundTheBody [[spoiler:Visser One, who more or less makes a career out of this.]]
* NeverSayDie: Completely averted, and kinda [[LampshadeHanging lampshaded]] when Rachel initially thinks "I'm going to destroy [[spoiler:David]]," but then she corrects herself: she's going to ''kill'' him. "Destroy" is a "weasel word" because it's vague and almost meaningless (the exact reason it's considered more family-friendly and often used in kids' fiction), whereas kill means ''kill''.
** When a bunch of Star Trek fans insist to help kids protect the Hork-Bajir's valley from a Yeerk onslaught all is splendid until Jake starts giving some last-minute orders, including "to move the wounded to safety but leave the killed lie." The father of the Trekkies family then asks timidly if by "killed" Jake meant "stunned or captured" and Jake replies that no, by "killed" he meant "killed to DEATH".
* NeverTrustATitle: Some of the later books got really bad about this. Titles like ''The Suspicion'' (where nothing is suspicious), ''The Prophecy'' (which features no prophecy), and ''The Hidden'' (which features a bizarre morphing buffalo that is definitely not hidden) come to mind.
** Strangely, these are all Cassie books. Make of that what you will.
* NiceJobBreakingItHero: Elfangor. Alloran's infestation by Visser Three was his fault.
** That and Seerow being responsible for the Yeerks becoming a danger in the first place.
** Jake's handling of David in ''The Threat'' also counts.
* NoBiochemicalBarriers: Hork-Bajir can eat Earth bark and Andalites can eat Earth grass. Yeerks can interface with all sorts of alien nervous systems, suggesting a common signaling system. Also, it seems DNA is very common, forming the primary building block of almost all living organisms around the galaxy.
** This could be justified by assuming that DNA is the only genetic molecule that works, so you can't ''have'' multicellular life without it.
*** Somewhat less probable is the fact that so many planets have life with cellular structures similar enough to animals for the process to work, though. It's not just DNA, or morphs would vary greatly in terms of weight and muscle tone (not to mention the clothing-and-hair thing), and the acquisition of the DNA (safely packaged in the nucleus of an animal cell) is a complicated question on its own. Let alone whatever nervous interface is used to trigger the morphing process based on visualization (although their ability to control morphs does suggest that the mind is at least partly independent of the brain in this universe). For the process to work, all species involved need improbably similar cell structures and embryology.
**** [[AWizardDidIt Ellimist did it?]]
* NobleSavage: The Hork-Bajir before their war with the Yeerks.
* NoCelebritiesWereHarmed: Jeremy Jason [=McCole=] (from #12) of the fictional TV series ‘’Power House’’, is totally not an expy of ''HomeImprovement''[='s=] Jonathan Taylor Thomas.
** And yet, real celebrities' names were dropped all the time. Noah Wyle of {{ER}} was mentioned a lot, and book 17 gives us no less than seven real celebrity names at the Planet Hollywood concert. Cassie and Jake even use David Letterman as a code word when talking about [[SixthRangerTraitor David]] in an insecure phone conversation.
** They also meet a world leader at the summit in the David trilogy who is almost certainly Boris Yeltsin.
* NoEnding: Oh yeah. It approaches MindScrew territory.
* NoExceptYes
* NoMouth: Andalites.
* NoNameGiven: All of the protagonists except Ax. In #23, Tobias' last name is transcribed as "______" in dialogue; however with the revelation that Elfangor as a human nothlit was Tobias' father, and that Elfangor went by the name "Alan Fangor" it is assumed that Tobias' last name as of or after the will reading at the end of #23 is Fangor. The revelation of Jake's last name ([[spoiler:Berenson]], which is probably also Rachel's) is used to highlight the seriousness of the new situation.
** Actually Tobias' last name was more likely to be the last name of the man who "married" Loren after the Ellimist erased her memory of Elfangor. In ''TAC'', it reads: "I saw Loren, and wrapped around her time line now was another human who would be her mate. I had been written out of her memory." (Tobias has the DNA of Loren and Elfangor's human ''Frolis Maneuver'' morph, but was raised as a baby by Loren and this other man.)
* NonSequiturThud: Tobias crash-lands into a window and starts rambling about ''TabletopGame/{{Clue}}'' at one point.
* NoOneGetsLeftBehind: Particularly memorably in #41 The Familiar.
* NoPaperFuture: Used to comedic effect and to demonstrate Applegate's mild dislike of computers: Ax can't believe that books were invented before computers, because he finds them much quicker and easier to use. (He's also surprised that the telephone was invented before the chat room.)
* NoSenseOfHumor: All of the Andalites, besides a few like Ax and Arbron.
* NoSidepathsNoExplorationNoFreedom: Alternamorphs #1 is a rare literary example. Despite ostensibly being a ChooseYourOwnAdventure type gamebook, the author doesn't seem to understand the concept, because the story is completely linear and every "wrong" choice results in instant death. Oddly enough, the second book went to the opposite extreme to the point of unintentional deconstruction.
* NostalgiaFilter: An in-universe example: at the end of the series, Marco sees the years he spent fighting Yeerks as the "good old days". He remembers life-and-death battles as "cool, rock 'em sock 'em battles". He doesn't really seem to remember how much they scared the crap out of him at the time. But then, it's said that Marco has a much easier time adjusting to civilian life than the others, because he doesn't feel guilty about the things he's done.
* NothingIsTheSameAnymore: After Visser Three's [[spoiler:promotion to Visser One]], the war quickly escalates and missions become increasingly important. This culminates in the discovery of the "Andalite bandits'" true identities. The seriousness of the kids' new situation is highlighted by the revelation of Jake's last name.
* NotQuiteDead: After David leaves the barn, Jake sends Tobias to follow him. When Jake catches up, [[spoiler:David says that he's killed Tobias, and Jake sees Tobias' mangled corpse. But as it turns out, that wasn't ''really'' Tobias, just an innocent red-tailed hawk that happened by. David had simply lost Tobias early in the evening, and the latter had spend a good couple hours trying to find him.]]
** While the Helmacrons and the kids are inside Marco's body, he morphs into a cockroach. The Helmacrons shoot Marco's heart, rendering him ostensibly dead. [[spoiler:But, as Cassie suddenly recalls, stopping a cockroach's heart doesn't kill it - they have a backup system.]]
** Spoken word-for-word near the end of the final battle:
--->'''''Visser One''': So. Still not dead.\\
'''Jake''': No, visser, not quite dead.''
* NotSoDifferent: There's some angsty speculation among the kids that taming and controlling their morphs' natural minds is the same as what the Yeerks do. Likewise the whole-sale slaughter of Yeerks, and the possible comparisons to terrorist attacks on civilians.
** Cassie gets an entire book dedicated to this in #19: The Departure
** Crayak also does this with Rachel.
** Also done with [[spoiler:the Howlers]] and the Pemalites, two alien species created by Crayak and the Ellimist. The [[spoiler:Howlers]] look like AlwaysChaoticEvil who kill everything in their path and the Pemalites are insanely pacifistic, but the two races, thanks to how they were designed, [[spoiler:actually had the exact same priority in life: to have fun. Their creators just gave them different ideas of 'fun']].
* NotSoExtinct: The Venber in "The Extreme". Though they're actually hybrids of Venber and humans brought back by the Yeerks.
* NotWearingTights: Kinda.
* NumberTwo: Marco fits the traditional role of TheLancer, but Tobias seems to fit this role. Jake usually appoints him leader of the Marco-Tobias-Ax sub-team, which ended up carrying the end of the war.
* ObfuscatingStupidity: A favorite strategy of Marco's.
* OddFriendship: Tobias and Ax.
* OfficialCouple: Jake and Cassie, Rachel and Tobias.
* OffWithHisHead: Visser Three's preferred method of execution, though he's a fan of torture as well.
* OhCrap: A couple times, but most notably in the second-last and last books. First, when [[spoiler:Visser One realizes that the Animorphs have gotten onboard the ship]], and second, when [[spoiler:Tom discovers he's been had and the kids are still alive.]]
* OhGodDidSheJustHearThat: The Leerans are fully-capable mind readers. As are, naturally, the Animorphs when they morph Leerans. Their first conversation in Leeran morph is... ''awkward''.
** ''"Um, I'd just like you all to know," Marco said loudly, "that whatever thoughts you may be hearing are completely made up. They're not real."''
* OnceAcceptableTargets: The Yeerks are an in-universe example. In early books the kids (especially Ax) can't overemphasize how evil they are, talking about how they'll [[ForTheEvulz destroy the environment because they can]] and [[AcceptablePoliticalTargets comparing them to Nazis]]. But as the war goes on they grow to realize that not all Yeerks are cackling villains like Visser Three and even gain allies from the other side in the form of the Yeerk Peace Movement.
* OneWingedAngel: Technically all of the "battle forms" count, though Visser Three gets to do a classic example at least once every few books.
* OnlineAlias: Mostly features the "modern" kind: [=YeerKiller9=], Gump8293, Bball24, etc. But it also has some more hacker-like ones, like "Govikes" and "[=YrkH8er=]". The Ketrans use gaming names as well.
* OpenSaysMe: In ''The Warning'' Jake morphs a rhinoceros to invade Joe Bob Fenestre's home. The other Animorphs have to guide him due to the rhino's poor eyesight, and frequently have him 'open doors' where none existed before.
* OptOut: Right before the final battle, a lot of the Auxiliary Animorphs decide that they want to sit it out, due to the fact that their friend Ray was recently killed. Jake doesn't really care and makes them go anyway. ("We didn't give them morphing power so they could have fun flying around. This is when we need them. All of them. You're their leader, James, so lead.") [[spoiler: They then all get killed, which Jake expected to happen.]]
* OppositesAttract: Rachel and Cassie.
* OurCentaursAreDifferent: Andalites are blue centaurs with scorpion tails and stalk eyes. In one book, a TV show gets a few seconds of an Andalite on film and wonders if it proof that centaurs exist.
* OrdinaryHighSchoolStudent: All of them ([[TokenNonhuman excluding Ax of course]]). And Tobias, after the first book.
* OrganicTechnology
* OrificeInvasion: The Yeerks. In the ''ear''.
* OtherMeAnnoysMe
* OutGambitted: Visser One's plan worked well. Tom's worked even better. Jake's worked best of all.
* OverlyLongName: [[spoiler:The Ellimist's real name is Azure Level, Seven Spar, Extension Two, Down-Messenger Forty-One. Ketrans' names are basically their address, which is why they tend to call each other by their chosen names or gaming handles, and his was Ellimist.]]
* PainfulTransformation: Actually, it's specifically mentioned that while there's no actual pain, it definitely feels like there ''should'' be.
* PantheraAwesome: Big cats make good battle morphs. Jake's main morph is a tiger, while David and James both had lion morphs. There were also times when the whole group morphed jaguars and cheetahs. Hell, even Tom's favourite battle morph is the jaguar.
* ParentWithNewParamour: Marco's dad eventually marries Nora Robbinette, his son's ''math teacher.'' [[spoiler:It doesn't last. Eventually, he's reunited with his NotQuiteDead first wife, and Nora becomes a Controller. Marco, either because it'll be easier on his father or because he wants to see his parents together again, lets him think that Nora was always a Controller. God only knows what happened to the dog...]]
* ParentalAbandonment: Tobias' dad is dead ([[spoiler:his dad is Elfangor, by the way]]), the other is [[spoiler:blind and therefore unable to take care of him.]] Tobias is "raised" by his aunt and uncle, neither of whom want anything to do with him.
* ThePasswordIsAlwaysSwordfish: The access code for the Pemalite spaceship is '6'. That's it. Just '6'. It's justified, in that the Pemalites were incredibly peaceful and trusting. [[RealityEnsues They are also all dead; and the Yeerks cracked the code in about a second]].
* PathOfInspiration: The Sharing.
* PatrickStewartSpeech
* PayEvilUntoEvil: [[spoiler: Jake, before flushing the Pool into space, decides that Yeerks are subhuman parasites who deserve nothing but cold, frozen death: "They could've stayed home, I thought. No one had asked them to come to Earth. No more than they deserved. Aliens. Parasites. Subhuman."]]
** Also, Marco isn't very good at hiding the fact that he takes pleasure from killing Yeerks. In #19, he tells Cassie, "You don't make peace with parasites. You don't turn them around. You bury them."
*** It eventually subsides, though, as part of Marco's CharacterDevelopment; over the course of the series he becomes much less emotional, which makes him a more effective strategist.
* PercussivePrevention: When Ax realizes that the only way to avert a world war in book #46 is to [[spoiler:threaten the Yeerk pool, and everything above and around it, with nuclear destruction]], Jake, naturally, objects. Ax knows he can't force Jake to have any responsibility for it, so he calmly knocks Jake out.
* PerfectPacifistPeople: The Pemalites, a ridiculously peaceful race who were completely obliterated by a more militaristic species. Tragically, their incredible technology could have been converted into weapons that would easily destroy their opponent, but as a species they couldn't bear to do so.
** There's also the Hork-Bajir, who while not as advanced, were also totally peaceful, and were enslaved when they caught the attention of a more aggressive race. Notable in that both of these species were created artificially, and designed to be non-violent by their creators. The series seems to give the impression that while being a pacifist sounds great, in reality it isn't a good survival tactic.
* PhlebotinumBreakdown: Happened a couple of times with BodyHorror-riffic results. Rachel suffered a case of InvoluntaryShapeshifting, turning into crocodiles, ants, and elephants at inconvenient times. Marco got it even worse, turning into a series of TwoBeingsOneBody creatures. (Dude. Osprey-Lobster. Trout-Gorilla. Neither of which could breathe. And, of course, the mighty poo-bear! [Poodle-Polar Bear.])
* PlanetOfHats: The Iskoort.
* PlayfulDolphin: As you'd expect, the dolphin morph is pretty playful. [[spoiler:Marco and Cassie force Jake to morph dolphin in an attempt to counter his depression with the dolphin's natural chirpiness]].
* PluckyGirl: Loren. She's Rachel Lite.
* PopulationControl: Mentioned for the Andalites in ''The Andalite Chronicles''.
* PowderTrail: The villain uses this to blow a hole in ''HMS Victory'' in ''Elfangor's Secret''.
* PowerAtAPrice: To quote Jake: "''The power made us responsible, see. Without the power the knowledge would have just been a worm of fear eating up our insides. Bad enough. But it was the power that turned fear into obligation, that laid the weight on our unready shoulders ... Power enough to win? No. Power enough to fight? Ah, yes. Just enough, little Jake, here is just enough power to imprison you in a cage of duty, to make you fight...''"
* PowerNullifier: The anti-morphing ray.[[hottip:*:Though we never actually find out if it works—the Animorphs just manage to convince the Yeerks that it doesn't.]]
* PowerOfFriendship: Corrupted by the imitation abilities of the Yeerks.
** But Marco and Jake's friendship is a theme in the series. Jake and Marco have been best friends since they were old enough to talk, and are immensely loyal to each other. It's said that Marco only initially joined the war effort because of his loyalty to Jake, and throughout the series that loyalty is the source of many [[CrowningMomentOfHeartwarming crowning moments of heartwarming]]. Marco is the only one who ''never'' criticizes Jake when it's apparent that he's already under a lot of stress, notable because normally 99% of criticisms come from Marco.
*** Made even more heartwarming by the fact that Jake is the only person Marco really respects. Everyone else just brings out Marco's sarcastic DeadpanSnarker mockery.
* PowerTrio: Marco, Ax, and Tobias were often sent alone on missions, especially near the end of the war. Ax and Marco switched off, but Tobias was always Ego/Kirk.
* PowerParasite: Following this trope ''literally'', Yeerks use other creatures as hosts for their specific abilities.
* PraetorianGuard:
** Visser Three's Blue Band Guard. Named after the blue armbands they wear.
** Also, the Orff, a race of aliens who act as security agents to the Council of Thirteen.
** In early books, Visser Three and Visser One had red and gold-armored guards respectively. It was stated each Visser had their own private security force, each with different colors.
* PragmaticVillainy: Subverted with Visser One.
* PrettyBoy: Ax, in his androgynous male human morph, which is made of DNA from Rachel, Cassie, Jake, and Marco.
* ProperlyParanoid: All the kids to some extent, but Marco takes it really really far, mostly because he's the most afraid of dying.
-->Marco: I'm paranoid, sure. But that doesn't mean I don't have enemies.
* ProudWarriorRaceGuy: Ax, though it's explicitly said that Andalites aren't really a warrior race. Andalites are ''supposed'' to love peace, and spending time with their families, and communing with nature, and so forth. But Andalite warriors, while pretending to love those things, are really only interested in fighting for the glory of the Andalite people.
* ProudMerchantRace: The Iskoort.
* PunctuatedForEmphasis:
-->'''Jake''': [[ItMakesSenseInContext CATCH! THAT! BUTTERFLY!]]
-->'''Rachel''' (in a different book): Don't. Touch. Me.
* PuppeteerParasite: The Yeerks.
* ThePurge: Late in the series, a massive campaign to reorganize the Yeerk Empire begins, headed by Visser Three. [[spoiler:Visser Three convinces the council that Visser One is a traitor, and she is executed. Visser Three usurps her position and kills everyone loyal to her, replacing them with his own subordinates]].
* PsychicPowers: Leerans, Andalites, the Ellimist, Crayak...
** Andalites are not actually psychic. Thought-speech seems to be a physically measurable phenomenon (the Nisk had thought-speak detectors; Andalites have thought-speak microphones) present in the brains of some species that allows them to broadcast thoughts. Even more supported in that only linguistic information can be transmitted, suggesting that the transmitter is located in the language centers of their brains. Apparently absolutely any brain can act as a receiver without any specialized neural structures.
*** Further supported while simultaneously providing an explanation for why the morphing technology grants thought-speech to those in morph. If an Andalite's thought-speech transmitter was a physical structure in their brains, they would lose it during a morph and thus be unable to thought-speak unless the morphing technology included that feature.
* PsychicStatic: John Berryman, Jr. thinks ''Henry V'' at Visser Four, so much so that the ''very first thing'' he does when he finds the Time Matrix is try to change the result of the Battle of Agincourt so that Shakespeare would never be inspired to write it.
* PsychoForHire: Taylor.
* PunnyName: "Animorphs", a portmanteau of Animal Morphers, was a name originally devised as a joke by Marco, reminiscent of the Justice League and other superhero team names. The kids more or less jokingly adopt the name, but refer to themselves as "the Resistance" or something similar to outsiders. By the end of the war, their enemies begin [[CompletelyMissingThePoint seriously calling them Animorphs]], and they begin calling themselves Animorphs seriously as well.
* PutOffTheirFood: In ''The Android'', Marco's parents try to serve him chicken for dinner after he was nearly killed by a bird while in spider morph. Marco opts out.
[[/folder]]

[[folder:Q-T]]
* TheQuisling: Chapman in ''The Andalite Chronicles'' and Taylor in ''The Illusion''. David threatened the Animorphs with this, but it's heavily implied he's bluffing and hates the Yeerks as much as they do.
* QuitYourWhining: Jake does this to Marco in ''{{Animorphs}}'' #35, helping him to recover from his ShapeshifterIdentityCrisis. Marco also does this to Rachel in #37 (in what many people see as a CrowningMomentOfAwesome) snapping her out of HeroicBSOD.
* RagtagBunchOfMisfits: Subverted; while a bunch of kids aren't what you'd call a stellar planetary defense army, they turn out to be remarkably good at it, especially Marco.
** Gets [[DeconstructedTrope deconstructed]] in #38. The Andalites send an expendable team of [[MilitaryMisfit military misfits]] to earth on a shadowy secret mission that involves manipulating the Animorphs, only to be clearly outclassed by the (by now) extremely disciplined and battle-hardened Animorphs. Comes complete with a ReasonYouSuckSpeech / ScrewYouElves to the Andalite leader that becomes a mini-[[CrowningMomentofAwesome CMOA]] for Jake.
* RammingAlwaysWorks: In the series' arguably most iconic instance, [[spoiler: the final line in the series is Jake giving the order to ram an enemy ship, which could kill four of the Animorphs. Since it's a BolivianArmyEnding,]] we don't know whether it works or not.
** Also, Elfangor wins a battle by using this same desperate tactic in ''The Andalite Chronicles'' -- [[spoiler: thus making the series' ending a MythologyGag.]]
* RealityEnsues: [[spoiler: The war ends. But Rachel, Tom, Jara Hamee, James and presumably ''all'' of the auxiliary Animorphs are dead. The Blade ship escapes, Visser Three is captured but not executed. Jake is left a broken man due to his actions in the war, he and Cassie break up, and Tobias leaves society. Marco does become famous, but it's hollow. It is in short, exactly what would really happen after a war ends]].
* RealityWarper: The higher powers Ellimist and Crayak, as well as Crayak's servant the Drode.
* ReasonableAuthorityFigure: The governor of California. No, not Arnold Schwarzenegger.
* RebelliousRebel: David.
* RecruitTeenagersWithAttitude: Deconstructed. The teens win the war, but they suffer some pretty serious psychological damage in the process.
* RecycledINSPACE: The book ''The Hork-Bajir Chronicles'' is not dissimilar to {{Pocahontas}}, [[GenderFlip gender-flipped]], IN SPACE.
* RedshirtArmy: The actual US Army, as well as the [[spoiler:auxiliary Animorphs]], in the last battle. Toby's Hork-Bajir army get killed a lot, too, near the end of the series.
* ReluctantWarrior: Cassie
* TheRemnant: Referenced. [[spoiler:The Blade Ship's crew may qualify]].
* RetGone: [[spoiler: Visser Four's host]]
* RevengeByProxy:
** See PayEvilUntoEvil. [[spoiler:Jake is pretty pissed that Visser One has gleefully slaughtered the Auxiliary Animorphs, so he's willing to massacre seventeen thousand Yeerks, who just happened to be completely defenceless and harmless.]]
** [[spoiler:Also, after they learn the kids' true identities, the Yeerks attack their houses, managing to enslave Jake's parents.]]
* RewardedAsATraitorDeserves:
** [[spoiler:David]] is a subversion, as [[spoiler:the ''heroes'' are the ones that mete out his karmic punishment rather than the villains he threatened to betray them to.]]
** Played straight with [[spoiler:Tom.]]
** Chapman, as a teenager, tries to offer the human race to the Yeerks in order to save himself, which is ultimately what starts the invasion and leads to his own infestation.
* RichardNixonTheUsedCarSalesman: Hitler is implied to be this in ''Elfangor's Secret''.
* RightWingMilitiaFanatic: Probably what at least some of the terrorists mentioned briefly in the last book were supposed to be, since it Jake says some are religious extremists, some are conspiracy nuts, and some are racists. He says that some are eco-terrorists though, so at least some of them don't quite fit the mold.
* RobotBuddy: Erek King. But [[spoiler:he and the kids have a falling out at the end of the series, because Jake blackmailed him into fighting, which he's programmed never to do. Conversely, the kids blame Erek for the death of Rachel, as Erek drained the Pool ship's weapons. Erek and the Animorphs never reconcile.]]
* RoboticReveal: Suspicions are aroused when the Animorphs-as-dogs realize that Erek has no scent, but it's not until Erek is hit by a truck and the Animorphs get a good look at him through the eyes of a wolf spider that they realize that Erek is an android.
* RockBeatsLaser: Very much so
* RooftopConfrontation
* RoyalsWhoActuallyDoSomething: In Andalite society, "Prince" is a military rank... So it stands to reason that princes would actually do some fighting.
* RubberBandHistory: ''Elfangor's Secret'' opens in the world where Visser Four's time travel plans went on unchallenged. Jake calls himself "Supreme Leader" and is considering turning Cassie in for possibly opposing the genocide in South America. Everyone, Cassie included, owns a slave. Melissa has replaced Rachel, who's in a reeducation camp. Oh, and ''Pong'' has just debuted, and cable television is nowhere to be found—there’s only one heavily censored channel.
* RubberForeheadAliens: Oh so very averted. Not only do ''all'' the other alien races look nothing like humans, but it turns out that humans are the only alien civilization in the universe that walks upright on two legs.
** Well, Hork-Bajir have two legs, but they have their tails for balance.
** WordOfGod is that Applegate originally intended to use RubberForeheadAliens just in case the series got a LiveActionAdaptation. Then Scholastic rejected the idea and told Applegate to be more creative. So she did and made the aliens damn-near ''IMPOSSIBLE'' to adapt to live-action ([[TechnologyMarchesOn at the time]]). Then the TV series was made and we all know [[AdaptationDecay how that turned out.]]
* RuleBreakerRuleNamer: The Law of Seerow's Kindness.
* RunningGag:
--->'''Jake''': Ax?
--->'''Ax''': Yes, Prince Jake?
--->'''Jake''': Don't call me prince.
--->'''Ax''': Yes, Prince Jake.
** Jake eventually lampshades it as a running gag between them. He also specifically notes that if he ''doesn't say'' "Don't call me prince", it's a sign of how serious the situation is.
* SadClown: Marco.
* SamaritanSyndrome: ''Marco'', of all people. Though all the kids have it to some degree.
* SapientCetaceans: Cassie has a minor crisis because she's not sure if it's right to take a dolphin's DNA or control its mind; one of their rules is that the Animorphs never morph a sapient creature without its permission, or unless it's an urgent emergency. Whether or not they're truly sapient is never quite settled (although whales just barely are, according to the Drode), but they are capable of a kind of telepathic communication with whales ("great ones;" the dolphins are the "little ones."), and Cassie firmly believes they have souls. Everyone loves the dolphin morph, because they're so happy and carefree.
* ScrewTheRulesIHaveSupernaturalPowers: The Animorphs make a rule not to do this, but break it all the time in early books, usually for opening chapter hijinks. [[spoiler:It comes back to bite them ''hard'' during the David Trilogy, when the eponymous character takes that idea and runs with it.]]
* ScrewThisImOuttaHere: Marco, until he discovers that [[spoiler:his mother is Visser One]]. Cassie, temporarily, on more than one occasion. And David in ''The Threat''.
* ScrewYouElves: From #38:
--> '''Jake:''' Andalites are very fast, those snakes are faster. One move from your boys and they will die... Now we stop playing games, you're not the Andalite fleet, and I'm not going to snap a salute and say 'Yes Sir!' We deal as equals. Which, to be honest, is generous of us under the circumstances.
-->'''Gonrod:''' I command here. Am I clear on that?
-->'''Jake:''' No, sir. This is Earth. This is a human planet. We are not the Hork-Bajir, we know how you 'rescued' them. As long as you're on earth, you'll get along with us. Am I clear on ''that?''
* SealedRoomInTheMiddleOfNowhere: The Animorphs condemn David to one, leaving him on a rocky deserted island in the middle of the ocean.
* SecretKeeper: The Animorphs themselves are Secret Keepers for the existence of the [[MechanicalLifeforms Chee]], the location of the free Hork-Bajir, and the fact that Aftran and Illim/Mr. Tidwell are members of the Yeerk Peace Movement, while these factions are all Secret Keepers for the Animorphs' identities and the fact that they're mostly human. This becomes a huge problem when Visser Three captures and intends to interrogate (read: torture) Aftran. Later, [[spoiler:Visser One and the Animorphs become mutual Secret Keepers for political/strategic reasons, and even later, the Animorphs bring in their families for their protection.]]
* SenseFreak: Ax in human morph, as Andalites are mouthless ("Cinnamon BUNZAH!!!"). The Yeerks aren't as obvious about it, but possessing a host is the only way they can enjoy the senses other species take for granted - Visser 3's favorite is sight. [[spoiler: His punishment after the war is simply to be kept alive in his slug form.]]
* SetRightWhatOnceWentWrong: ''Elfangor's Secret,'' although it was more like "re-set what was originally kinda going okay but this one guy fucked up and the Ellimist and Crayak are panicking now."
* ShapeshifterMashUp : Marco in The Proposal. He morphs a osprey/lobster mix, a spider/skunk mix and a polar bear/poodle mix, respectively.
** Might also be said of anyone who uses the Frolis maneuver to create a morph of the DNA of several individuals of a species combined.
* ShapeshifterModeLock: More than two hours in a morph traps you in that body. [[spoiler:There are an alarmingly large number of characters who fall prey to this fate[[hottip:*:Although many did so voluntarily]] - Tobias, Elfangor, David, Aldrea, Aftran, Menderash, the ENTIRE TAXXON RACE, and temporarily Cassie.]]
* ShapeshifterShowdown: Both the Animorphs and Visser Three have shapeshifting powers, so these are common enough. The most extreme example is probably in ''The Return'', where Crayak pits Rachel and Visser Three against each other in a gladiatorial battle and they both strategically change forms constantly throughout the fight.
* SharingABody: Controllers (Yeerks and their hosts). Also Cassie and Aldrea in ''The Prophecy''.
* SheepInWolfsClothing: Marco pretending to be a Controller.
* ShellshockedSenior: [[spoiler:Jake]], by the time he's eighteen.
* ShootTheMessenger: Visser Three, all the goddamn time.
* ShootTheShaggyDog: "The Hork-Bajir Chronicles". At the end of the story, all the Hork-Bajir except Aldrea and Dak are either infested or dead, the Andalites successfully sent out the quantum virus, and the yeerks are now ready to rampage around the galaxy to their heart's content.
* ShootYourMate: Visser Three tries to get Visser One to [[spoiler:shoot one of her human kids]].
* ShoutOut:
** Amusingly enough, the name of the mind-controlling slugs is an anagram of the middle name of Senator John Yerkes Iselin from ''TheManchurianCandidate''. However, according to WordOfGod, the Yeerks in ''Literature/{{Animorphs}}'' take their name from Creator/JRRTolkien's [[ConLang Sindarin]] Elvish word for Orcs, ''yrch''.
** More Tolkien references include Ax's middle name, Esgarrouth, derived from the Middle-Earth town of Esgaroth. In ''The Unknown'', the air force base personnel use the cover identity "Gondor Industries" on their night out at The Gardens.
** Also many, many more subtle and insignificant ones, such as the six dolphins named after the main characters of ''{{Friends}}'' in book #4.
** Generally, Applegate references her favorite things often in the series: ''Franchise/StarTrek'', the Rolling Stones, the Ford Mustang, Dr. Pepper, et cetera.
** In ''The Solution'', Rachel has a dream in which she morphs elephant in a crowded mall. She crushes a kid in an orange jacket, prompting someone to say, "[[WesternAnimation/SouthPark Oh, my God! She killed Kenny!]]"
** Marco's recommendations for Ax to watch in ''The Experiment'': Series/BuffyTheVampireSlayer, Series/PartyOfFive, Series/{{Cops}}, and WesternAnimation/SouthPark.
** Marco also mentions Buffy the Vampire Slayer to be his favorite show in ''The Discovery''.
* ShownTheirWork:
** In amongst all the alien warfare, there are detailed descriptions of about a hundred different animal species. Applegate clearly researched a lot of the morphs and went to great lengths to detail them accurately.
** Applegate also dabbles in military history and literature from time to time.
** When turning into a bee, Marco describes a color so unbelievably intense humans can't see it, but bees can. He's seeing ultraviolet, which many flowers use to attract bees.
* SillyRabbitIdealismIsForKids: Marco, often.
* SillyRabbitCynicismIsForLosers: Marco himself also notes this to Rachel while Jake is out of commission. They need a fast, straightforward {{plan}} for a high-risk rescue, and he explains that that's not his territory -- his cynicism makes him too cautious to address that situation, [[TheLeader so she needs to lead.]]
* SixthRanger: David is the straight example, identified on book covers as the "Sixth Animorph". [[spoiler: He did a FaceHeelTurn pretty quickly, though]]. Ax is the more commonly accepted example, though the books gave the subtle implication that [[MyFriendsAndZoidberg as an Andalite Ax wasn't a true Animorph]]. James and the Auxiliary Animorphs count as ''eighth'' rangers.
* SlapSlapKiss: Almost completely averted. Rachel and Marco had a very antagonistic relationship, but she and Tobias were pretty much an item from day one. Not completely, because Marco makes several comments indicating he might have a mild crush on Rachel (although his perception that she's certifiably insane balances it out), "[[StarfishCharacter Nice Rachel]]" says flat-out that she would probably go out with Marco if he asked her, and in the WhatIf / WonderfulLife book "Back to Before", they actually ''did'' go out.
** Basically, a running theme of the series is that war ruins everything. In the early books, while Rachel was definitely loyal to Tobias, she and Marco were constantly fight/flirting just like any two good friends who were possibly attracted to one another might. By the end of the series, all of the fun and flirting has gone out of their relationship, and the fighting is not only real but also very cruel and personal.
* SlidingScaleOfIdealismVersusCynicism: The series starts out on the idealistic side, and ends more on the cynical side. The gist of the series is pretty much that the universe is a violent, dangerous and evil place, and things are bad all over, but we should try to do the right thing as often as we can anyway. To quote Jake: "It was a stupid, naive, idealistic and childish decision. But I wouldn't want to live in a world where we didn't try the stupid, naive, idealistic and childish thing sometimes."
* SlumberPartyPloy: Used occasionally.
* SmarterThanYouLook: You don't want to mistake Rachel for a [[TheDitz ditz.]]
* TheSmartGuy: Ax, because he's an Andalite and therefore knows a lot more about science. But Marco's smarter than Ax is in terms of actual intelligence.
* SmugSnake:
** Marco. He's the only guy that Jake will let get away with constantly insulting him.
** You don't see it much, but Tom.
** [[SixthRangerTraitor David]].
** Ironically, all three of these characters are seen ''[[ScaledUp actually morphing]]'' snakes. Not too subtle, K.A.
* SoapBoxSadie: Cassie often voices her opinions on issues she considers morally compromising. The other characters (and the readers) sometimes get annoyed with this.
* SpaceIsAnOcean
* SpikeShooter: One of Visser Three's morphs can do this.
* SpikesOfVillainy: The kids have a hard time accepting the fact that unhosted Hork-Bajir are, in actuality, good guys, due to the dangerous-looking blades the cover the Hork-Bajir figure.
* SpockSpeak: Ax. The author is very particular about it; it is carefully stated that Ax picks up actions like nodding his head and shrugging his shoulders from talking to the kids a lot.
* SpySpeak: Periodically lampshaded by Marco, but mostly used in telephone conversations to arrange meetings.
* StableTimeLoop: Ocassionally.
** In #13, ''The Change'', the Ellimist sends Tobias back to the night before the infamous construction site incident that started the whole series. Tobias thus convinces his past self to team up the next evening with Jake and Marco and then to take that shortcut across the shady construction site.
** In ''In the Time of Dinosaurs'', the Animorphs are sent back to the last days of the Cretaceous. They ally with good aliens, the Mercora, against bad aliens, the Nesk, and steal a nuclear explosive from the Nesk to attempt to return home. The defeated Nesk leave the planet but send the Mercora a parting gift, [[spoiler:diverting a nearby comet to impact their settlement. The Mercora plan to use the nuke the Animorphs stole from the Nesk to destroy the comet. Tobias, realizing the comet is the very one that caused the K-T mass extinction and that nobody can ever find evidence of the Mercora, has Ax make the explosive a dud. The comet impacts, the Mercora and their settlement are annihilated. Conveniently enough, the comet impact is sufficient to return the Animorphs to their own time. With just one more thing to angst about.]]
** Also, the whole ''Elfangor's Secret'' book.
* StarCrossedLovers: Rachel and Tobias. She's a beautiful, smart, independent, funny and spirited suburban teenage hottie. He's a bird. And then "The Beginning" happens.
** Also Elfangor and Loren, who're not only from different species but separated by time travel, a meddling Ellimist and memory erasure. The end result: he's dead and she can't remember his existence.
* StarfishCharacter: #32, ''The Separation,'' in which Rachel is split into Mean Rachel and Nice Rachel. Everyone hates them both. And it involves an actual starfish too!
* StarfishAliens: Most aliens shown are such. Yeerks (parasitic mind-controlling slugs that feed off of radiation) Taxxons (giant centipedes with a crippling hunger that will eat themselves if they get wounded) and Andalites (Telepathic centaurs who eat out of their hooves) being the strangest, with everything else not far behind.
* TheStarscream: Visser Three to Visser One. [[spoiler:Tom's Yeerk somewhat also fits this trope. Near the end of the series, after Visser Three is promoted to Visser One, Tom betrays his leader to further his own ambition. (Although, to be fair, Tom is more interested in creating his own Empire as opposed to actually getting Visser One's job.)]]
* StayWithMeUntilIDie: Gafinilan and Mertil.
* StockYuck: Broccoli comes from aliens planting it here in the Cretaceous Period.
* StoryArc: The series can neatly be divided up into a couple story arcs. The first arc concerns itself with the development of the children into soldiers and [[{{Infodump}} explanations]] about morphing, the Yeerk invasion, et cetera. The second arc concerns itself with the day-to-day missions, and is cut in half by what you could call Story Arc 2.5, which concerns itself with the seventh Animorph, David. The third story arc deals with the escalation of the war and the reorganization of the Yeerk Empire - the execution of Visser One, Visser Three's promotion, Operation 9366, et cetera. The final story arc begins when the Yeerks discover the kids' identities.
* StrangeBedfellows: Rarely with Visser Three, occasionally with Visser One.
* StrangerInAFamiliarLand:
** Rachel in #48 ''The Return''. She has an internal monologue about how she feels isolated and apart even in a crowded school hallway.
** Jake, who can't relate to anyone after the war because they don't know what he's been through.
** Also, Tobias, as he's a hawk, and [[spoiler:since Rachel is dead,]] he has no more connection to humanity.
** And Ax. The things he's learned on Earth - the willingness to justify your actions to your subordinates, the acceptance of ''vecols'' as members of society - cause him to be seen as strange to other Andalites. Although, by this time, he's enough of a legendary war hero to get away with it.
* SubspaceAnsible: Z-Space communication.
* SufficientlyAdvancedAliens: The Ellimist and Crayak.
* SuperiorSpecies:
** Yeerks feel this way towards humans to some extent, but some can empathize with them (most Yeerks liken what they do to humans to what humans do to cows or pigs, but some realize that they steal others' bodies for themselves, and some realize that this is wrong)...
** Andalites are repeatedly characterized as arrogant, and see humans are curiosities at best and expendable inferiors at worst. (This provides an interesting twist: Jake and the others are waiting for a good part of the series for Andalites to save them, but Andalites don't give a damn about humans.)
*** Subverted in the last book. It's revealed that it's really only the Andalite military that's like this. Andalite civilians are much more agreeable and get along with humans just fine.
* SuperWeight:
** Type -1: Gedds, [[MinionWithAnFInEvil Karen/Aftran]], [[HandicappedBadass Mertil]], Taxxons, unhosted Yeerks
** Type 0: [[StarterVillain Principal Chapman]], Tom ([[BastardUnderstudy pre-morpher]]), [[BigBadWannabe Visser Four]], [[InsaneAdmiral Visser Two]]
** Type 1: [[CorruptCorporateExecutive Joe Bob Fenestre]], [[TheBaroness Taylor]], [[BiggerBad Visser One]]
** Type 2: [[ChildSoldiers The Animorphs]], [[SixthRangerTraitor David]], Tom ([[SmugSnake morpher]])
** Type 3: [[SixthRanger Ax]], most Andalites, Hork-Bajir, [[SmugSuper The Inspector]]
** Type 4: [[BigBad Visser Three]], [[BadassPacifist Erek King]] and the other Chee, Howlers
** Type 5: [[WildCard The Drode]], [[GeniusLoci Father]], Visser Four ([[ButterflyOfDoom with the Time Matrix]]), probably [[GiantSpaceFleaFromNowhere the One]]
** Type 6: [[AllPowerfulBystander The Ellimist]], [[GodOfEvil Crayak]]
** Type 7: The "greater power" referenced in #26 ''The Attack''.
* SurvivorGuilt
* SuperTeam: The Animorphs, of course.
* SupportingLeader: General Doubleday.
* TheSymbiote: The Iskoort. The "Yoort" descended from Yeerks who may or may not have been AncientAstronauts. They were parasites like the Yeerks of today, but they eventually realized the futility of it and made the conscious decision to modify their entire race as symbiotes with an artificially created lifeform, the "Isk".
* TakeAThirdOption: [[spoiler:A traitorous Tom presents a plan to capture the Pool ship to Jake. However, Jake sees through Tom's ulterior motives and realizes that Tom secretly plans to kill Jake and his friends when their usefulness has expired. Jake constructs his own plan which, with the help of Rachel and Erek, would both cripple the Yeerk Empire and neutralize Tom as a threat. It doesn't quite work out that neatly.]]
** David took one too. [[spoiler:Caught between the Animorphs and the Yeerks and unable to trust either, he turned on them both.]]
* TakeThat:
** #48 The Return, on describing the prospect of dramatizing the morphing process Rachel lists a handful of studios who she's convinced "wouldn't get it right." She explicitly lists Nickelodeon, who produced the ''Animorphs'' TV series, which Creator/KAApplegate has been vocal in her distaste for.
** Also, the Andalites were originally supposed to resemble stereotypical [[TheGreys Grey aliens]]. Scholastic [[ExecutiveVeto vetoed]] the original design and asked Applegate to be a little more "creative" so that if an ''Animorphs'' [[{{Series/Animorphs}} TV series]] was ever produced, they would have an interesting looking alien race to showcase. She then went ahead and made them as complex as possible--out of spite--to the point where they proved virtually impossible to properly dramatize when said TV series finally came into fruition. Take that, indeed.
** One of the most hated books is #28 The Experiment, which is loaded with plot holes and only exists to [[AuthorTract voice the ghostwriter's opinions]] about eating meat. Then the last chapter features the Animorphs all eating hamburgers, which was later revealed to be because KA Applegate didn't think much of the ghostwritten book and added that final chapter herself. The book's ghostwriter, Amy Garvey, was one of only two ghostwriters who were never allowed to write another Animorphs book again.
** From ''The Proposal'':
--> '''UPN Executive:''' You want to put this lunatic on the air? Try [[FoxNewsChannel Fox]], I'm not interested.
* TeamDad: Jake, who gets teased about it.
* TeamMom: Cassie sort of fits this role. She gives emotional support to the others whether they want it or not.
* TechnicalPacifist: The Chee in general, Erek in particular: [[spoiler:Erek helps the Animorphs capture the Pool ship because Jake threatens to kill a prisoner every time Erek refuses to cooperate. Erek finds both choices abominable but helps the kids to minimize casualties.]] Cassie may also qualify.
* TechnologyMarchesOn: ''#16 The Warning'', the "Internet is weird" book.
* TelepathicSpacemen: The Andalites and anyone who uses their morphing technology.
* TheTheTitle: Done with nearly every book in the series, excluding ''Visser'', ''Megamorphs 3: Elfangor's Secret'', and ''Megamorphs 4: Back to Before''. ''Megamorphs 2'' does feature "the" in the title, although it's not the first word: ''In '''the''' Time of the Dinosaurs''.
* TimeDissonance: Father (and, afterward, the Ellimist).
* TheyCallMeMisterTibbs: As an ''aristh,'' Ax needs a prince. Jake is that prince, much to his embarrassment.
* ThreeLawsCompliant: Some laws are deconstructed, some are averted: The Chee comply with the Third and Zeroth Laws, but their creators, the Pemalites, took the First Law to the logical extreme: no violence, period. As for the Second Law: [[spoiler:Erek refuses to obey Jake because he disagrees with his methods, so Jake uses the violence prohibition (in other words, the First Law) to manipulate him and force his hand.]]
* ThinkInText: The use of punctuation, <brackets>, to indicate thought-speech.
* ThisIsReality: The Animorphs are fond of either comparing their acts to superheroes' or of pointing out that said superheroes aren't real.
** Marco in particular was fond of doing this.
* ThroughTheEyesOfMadness: Rachel in ''The Return''.
* TimeAbyss: The Chee
* TimeMachine: The Time Matrix. Not really a machine, per se, but all we really know is that it was created by the Ellimist.
* TimeStandsStill: The Ellimist.
* TimeTravel : Many times.
* TrickingTheShapeshifter: Combined with enforced ShapeshifterModeLock to defeat [[spoiler:David]].
* TrademarkFavoriteFood: Ax and his intense, ''intense'' LOVE for cinnamon buns. He even keeps a picture of one in his makeshift home.
--> '''Marco''': Anyway, she tells me, 'Some kid went crazy and ate an entire pan of cinnamon buns.' Now, who, I ask you all, ''who'' do we know who would eat an entire pan of cinnamon buns?
* TomboyAndGirlyGirl: Rachel and Cassie, though which is which depends on the situation. In civilian life, Rachel is TheFashionista while Cassie is utterly fashion-blind (to Rachel's exasperation) and thinks nothing of getting her hands dirty with sick animals. In combat, Rachel turns into TheBigGuy and Cassie is the team's most reluctant fighter.
* TonightSomeoneDies: The cover quote of the final book is ''It began with six. It will end with five.'' Oh, NOW they get it right! Sort of. [[SixthRanger It REALLY began with five]].
* TookALevelInBadass: All the kids, really, though special shout-outs have to go to Jake in the last five books and David in his trilogy.
* TooManyHalves: Ax -- and by extension the Andalite race in general -- is once described as half blue deer, half centaur, and half scorpion. Then the narrator {{Lampshade}}s it by saying they realize that it's too many halves.
* TotallyRadical: Invoked by one of the characters. One comments that they'd "bet dollars to donuts" on something and another comments "Something your grandmother used to say?"
** The books themselves contain a lot of ''painfully'' [[UnintentionalPeriodPiece 90s slang]], or approximations thereof; "cool" brands, shops etc. are constantly namedropped. Part of the re-release's stated mission is to tone down the kids' slang (future-proofing, rather than simply "modernising" when that'll be outdated in ten years too) and remove references to specific clothes stores and the like.
* TouchedByVorlons:
** The Escafil Device (blue box), which gives normal beings the power to morph after contact with it.
** The Andalites themselves got a big speed boost to their evolutionary process when Toomin [[GoingNative went native]] with them in ''The Ellimist Chronicles''.
* TragicDream: Jake's weakness is his sense of responsibility: As long as he can, he feels he's got to at least try to save his brother Tom. Jake's entire motivation, right from the beginning, is to free his brother. As the years go by this becomes less and less likely. And it all culminates in the worst possible way: [[spoiler:As much as it pains him to do it, Jake orders his brother's execution.]]
* TragicHero: Jake.
* TrainingThePeacefulVillagers: The Hork-Bajir, both in ''The Hork-Bajir Chronicles'' and ''The Resistance.''
* TransformationTrauma: The books go on and on about how Morphing isn't nice to look at, often describing the process in excruciating detail.
* TranslatorMicrobes: All members of the Andalite military have translator chips implanted in their brains.
* {{Trickster}}: The Drode.
* TroublingUnchildlikeBehavior: They're kids. They kill people.
* TrueCompanions: Most obviously shown at the end of the series, when the kids see [[spoiler:rescuing Ax from The One]] as a moral obligation.
-->[[spoiler:'''Marco''': He told me the whole story. And every word was another nail in my coffin, because what was I going to do, refuse to save Ax? How many times had I been down for the count and only that lightning blue tail had brought me out alive?]]
* TwoActStructure: The secretive guerilla war, and the final story arc.
* TwoOfYourEarthMinutes: A RunningGag with Ax. It's heavily implied he's doing it to mess with Marco.
[[/folder]]

[[folder:U-Z]]
* UniversalDriversLicense: Marco. See IKnowMortalKombat.
* TheUnmasquedWorld: The last book. [[spoiler:We've got Hork-Bajir in Yellowstone, Taxxons in the Amazon, and Andalite tourism is a big thing]].
* {{Unobtainium}}: Ramonite, which Andalite (and thus, also Yeerk) ships were made of, can turn opaque or transparent or be completely reshaped to form open doors, all through computer commands.
* UnscientificScience: In "The Mutation", the explanation for how the Nartec came into existence makes no sense. The explanation is that radiation sped up their adaptation. That's ''really'' not how radiation works.
* UnusualEuphemism: The Hork-Bajir biology causes them to lapse into their native language, which is used to get cursing into the books. Context makes it clear.
* UnusuallyUninterestingSight: Among many others, the commercial scene in the third book.
* UnreliableNarrator: Most of the characters, especially early on, aren't capable of recognizing their own character flaws, and their narration is reflective of this. Furthermore, sometimes the kids just straight-up lie about things - see LiteraryAgentHypothesis. For instance, in the David trilogy, Jake says it's been a couple months since Elfangor's crash. Dialogue, however, hints that the story arc takes place much later, and it's confirmed late in the series that the David trilogy takes place maybe two years after the crash.
* UnresolvedSexualTension: Jake and Cassie for a good half of the series, before they make their mutual crush public. Also, Tobias and Rachel - it's the entire focus of their relationship, really, because Tobias is a bird.
* VeinOVision: Howlers use it to see weak points.
* VerbalTic: David has a tendency to say the name of the person he's talking to [[DepartmentOfRedundancyDepartment several times]] in a single conversation, usually when he's trying to be threatening. In one occasion in ''The Solution'', he says Rachel's name six times in one page.
* VetinariJobSecurity: In which Mr. Responsible Jake has to leave for a week and Rachel, who is, to put it diplomatically, something of a violence junkie, is made temporary leader. The end result is Cassie getting captured and dangerously close to the 2-hour limit.
* ViewerFriendlyInterface: The Pemalite ship.
* TheVirus: Yeerks.
* VitriolicBestBuds: Marco and Jake, who are best friends despite the fact that they argue more often than not.
* VillainBall: Visser Three, first by [[spoiler:being a total dick to the Taxxons and denying them access to the morphing cube when he got it]], and by [[spoiler:refusing to promote Tom's Yeerk.]]
** Not to mention killing Elfangor in the first book, when he could have infested him and then the Yeerk could have morphed the injuries away.
** And Chapman, who inadvertently caused his own infestation thirty years in advance.
** And David, who brought the entire Animorphs to their knees only to be beaten by suddenly developing BondVillainStupidity.
* VillainOfTheWeek: Sometimes. Notable examples include: [[TheNapoleon The Helmacrons]], [[OurMermaidsAreDifferent The Nartec]], [[{{Tykebomb}} The Howlers]], the SmugSuper Yeerk known only as The Inspector, and [[AxeCrazy Taylor]].
* ViolenceIsTheOnlyOption: Deconstructed. Is violence ''really'' the only option? At first glance, it seems that it is: Yeerks are stealing bodies by force and the kids have to stop them. But as the kids learn, Yeerks need bodies to properly live, and it's possible for the Yeerk and the host to have a symbiotic relationship. The problem is most hosts would resist infestation, which ''necessitates'' taking hosts by force. Cassie often tries to convince Yeerks that symbiotism is the best solution - and it works sometimes.
* VoluntaryShapeshifting: Lots of ShapeShifting Tropes too, eh?
* WagonTrainToTheStars: The journey that Marco, Santorelli, Menderash, Jeanette, Tobias and Jake take aboard the ''Rachel'' to find the Blade ship was, at least according to Marco. We never get the details of their adventures, though.
* WakeUpGoToSchoolSaveTheWorld: Not nearly as much as one would think, but most prominent in #22. By the end of the series, fighting Yeerks has been a full-time, round the clock job, so the kids rarely (if ever) go to class, instead getting the Chee to fill in for them.
* TheWallsAreClosingIn: In "The Separation", Visser Three used a moving wall because he thought the group were Andalites, who hate enclosed spaces.
* TheWarRoom: Where Jake first meets General Doubleday. Jake notes that it seems an awful like what you'd see in a movie; old guys chomping cigars, guys in suits and a [[TheBigBoard big map]] (that has his hometown crossed out, [[spoiler:presumably because ''it isn't there any more'']]).
* WarIsHell: The Aesop of the series, though not quite that simple, as it incorperates elements of WhatIsEvil, BlackAndGrayMorality, and ChildSoldiers.
* WarmBloodBagsAreEverywhere: The Taxxons. Mostly seen through the eyes of Arbron, and Tobias when he morphs Taxxon.
* WarriorPrince: In Andalite culture 'Prince' is a warrior's rank, so we see plenty of these.
* WasntThatFun: Marco does this all the time.
** Memorably played straight and subverted in Book #30. Marco, Tobias and Ax go sliding down several stories worth of staircase bannister in cockroach form on their bellies at warp speed. When they get off, they exult in how awesome it was... just before agreeing to '''never, ever''' do that again.
* WeAreTeamCannonFodder: The Auxiliary Animorphs, and the U.S. Army. In fact, that was the whole point.
* WeAreAsMayflies: The guerilla war between the Animorphs and the Yeerk Empire lasted three years and shaped the fates and lives of thousands of sapient creatures. The larger war between the Andalites and Yeerks was on a scale even larger. But in the end, the entire conflict was only a blip so small as to be unnoticeable when it came to the war between Ellimist and Crayak. The kids' war lasted three years, the war between Ellimist and Crayak lasted ''hundreds of millions'' or even ''billions'' of years, one that continues even after the Yeerk Empire is destroyed. If one looks at the series as a battle between good and evil, ''absolutely nothing was accomplished.'' What's one Yeerk Empire to Crayak?
** It's implied that the war is more critical than it seems, for reasons that will only be clear to the mortals of the galaxy a century or two down the line.
*** True, considering how much the Yeerk war influenced the budding, new conflict between humans, Andalites, Yeerks, ''Kelbrid'' and The One:
--->''"I command this ship," Efflit 1318 explained, "but I serve at the pleasure of The One Who Is Many. The One Who Is ''All''. We are not alone, Rakich-Four-Six-Nine-One. We are not ''this'' ship alone. We are the seeds of a new Empire that will far outshine the old, an Empire that will flourish under the leadership and wisdom of The One."''
* WeirdnessCensor: The reason that, when discussing who to recruit for the Auxiliary Animorphs, the kids decide that AdultsAreUseless.
--->'''''Marco''': It's got to be kids. Adults are too reality-bound. It's too hard for them to suspend disbelief for all this weirdness, even when it hits them square in the face.''
* WeirdTradeUnion: Book #26 has the Iskoort, whose entire society is apparently composed of {{Weird Trade Union}}s (see trope page for specific examples).
* WhatHappenedToTheMouse: Ax never really does avenge his brother's death, does he?
** There's a fair amount of these, actually: We never hear very much about Tobias, Cassie, and Jake's parents following the war, the being that caused Jake to see the alternate future in book ''The Familiar'', the fates of Mertil and Gafinilian, and whatever happened to Chapman and his family?
** ''The Return'' actually deals with ''exactly this'' in a somewhat literal form: [[spoiler:[[SixthRangerTraitor David]], who was trapped as a rat, comes back due to the interference of Crayak and tries to take revenge. And then begs to be killed after losing again.]]
** [[spoiler: Jake's parents are said to be freed after the war was over, and Rachel's mother was at her funeral. None of the parents, or Rachel's sisters, are mentioned again. As Tobias took off, it is unclear if he even stayed in contact with his mother.]]
** The aliens behind Book #41 are implied to not be the Ellimist or Crayak; but they neither revealed or mentioned again.
* WhatIf: ''Back to Before'': What if the Animorphs never met Elfangor? Things still would have blown up, that's what. Just faster and with ''even more'' angst.
** Also: What if the kids gave up? Earth becomes a Yeerk-infested hell, as you might expect, with the kids themselves becoming Controllers.
** What if Jake became too ruthless and cocky? In #41, Jake, in the heat of battle, leaves Marco and Rachel to fend for themselves, in order to save the rest of the team. The continuation of this mindset is shown in the far future: Tom suspected Jake of being an "Andalite bandit", and turned him into a Controller. Ax, Marco, and Cassie are taken, Rachel is gravely wounded in the ensuing battle, and Tobias escapes. Marco becomes host to Visser Two, and Ax becomes a key player in the attack on his homeworld. Cassie's Yeerk, Niss, joins the Evolutionist Front, a terrorist group dedicated to the creation of artificial hosts, led by Tobias, who permanently morphs Ax. But even Cassie and Tobias aren't good guys: Cassie becomes [[FutureMeScaresMe ruthless, cynical and practically evil]] ("In a war, Jake, anything is justified."), and Tobias is completely willing to let Cassie die to score a victory ("Save one, or save many? The choice wasn't so hard at the Ragskin building, when you left Marco and Rachel to save themselves.")
* WhatIsEvil: Frequently brought up. Yeerks need hosts, hosts need their freedom. Somebody has to lose. Are Yeerks evil because they fulfill their natural function? If that's the case, are humans evil for killing animals for meat?
* WhatMeasureIsAMook: Very low, until it's clear that the Yeerk-infected aliens are people too.
* WhatMeasureIsANonCute: At the start of the series, it seems this was, with a slug-like Yeerks as the bad guys and the mammal-like Andalites as the good guys. As per usual for ''Animorphs'', this doesn't stick.
-->'''Aftran''': What choice do we have? Back to the Yeerk pools? Back to our home planet, with Andalite Dome ships in orbit above us, waiting for one of us to rise from the sludge, then blow us apart? Leave the universe to the almighty Andalites and the species they happen to like?
* WhatMeasureIsANonHuman: {{Deconstructed}}. The Animorphs are less hesitant to kill when fighting Taxxons or Hork-Bajir rather than human-controllers. Visser One notices the discrepancy in human-controller casualties, confirming her suspicions that the "Andalite Bandits" are actually humans. Whoops.
* WhatTheHellHero: Fairly common, though usually ''just'' over the line. Rachel plays it well, Marco recognizes the need. [[spoiler: For the last two books, it's plainly stated that what Jake is doing is wrong, and he ''knows'' it's wrong, and ''everyone'' knows it's wrong, no one actually calls him out on it. By that point Jake has become such an unquestionable authority figure that no one, not even the kids' parents, are allowed to question anything he says or does. But at the end of the series, Erek and Visser One (!) have called him out on his actions.]]
** A slightly less serious example, but still in and of itself a WhatTheHellHero moment is when Tobias is at a dance with Rachel, in his human morph, and she tries to trap him in it so they can have a normal relationship. Tobias doesn't exactly call her out on it, because part of him isn't entirely convinced she wasn't right.
* WeaponOfMassDestruction: Ax is amused by "primitive" human nuclear weapons, and while humans haven't figured out cold fusion yet, Ax claims Andalites only use it to power children's toys.
* WeAreEverywhere
* WeComeInPeaceShootToKill
* [[WhamEpisode Wham Novel]]: Novel #23: The Pretender. [[spoiler: Prince Elfangor was Tobias' father. Tobias learns this in a literal ''wham moment'' while seated right next to a human-morphed Visser Three, pretending to be his cousin Aria offering him a real home... and he listens to it all while having to pretend he thinks his father is delusional and his "cousin" was a total nut.]]
** Turns into even more of a TearJerker when [[spoiler: the only reason Tobias survives the encounter is because he has ''forgotten how to show emotions as a human''.]]
** #49: The Diversion, where Tobias [[spoiler: discovers that his mother is alive and lives right near where he grew up. When he rescues her from Yeerks who want to enslave her to get to the Animorphs, he discovers that she is blind and amnesiac from a car accident when he was an infant. Giving her the morphing power restores her sight but not her memory.]]
** #5, too. [[spoiler:Sorry Marco, you're gonna need to kill your mama, at least twice.]]
* WhenAllYouHaveIsAHammer: Given that it's literally their only weapon, the Animorphs' practice and use of the morphing technology far surpasses the Andalites' skill with it. This to the point of shocking Andalites like Ax and Aldrea, who watch the humans perform morphing acts that would count as legendary to their species yet let it pass without comment.
* WhereTheHellIsSpringfield: "Hard to explain elephants and rhinos attacking here in... well, never mind where ''here'' is."
** Eventually averted in the last book, when the series is revealed to have taken place in California.
* WhyDidItHaveToBeSnakes: Tobias and going under water. Justified, though, given his species. Also, Ax, and other Andalites, are claustrophobic. Ketrans (the Ellimist's species before he ascended to near-godhood) can have panic attacks when indoors.
* WhyWontYouDie
* WiseBeyondTheirYears: All the kids, to some extent, but Jake mostly.
* WithGreatPowerComesGreatInsanity: Certain forms, like ants, can rob one of sentience for a while. It's not always predictable, either.
* AWizardDidIt: A lot of improbable things are chalked up to Ellimist and Crayak, such as the impossibly pacifistic Pemalites, the {{Contrived Coincidence}}s in the Animorphs lineup (see the entry above on CantStayNormal), David finding the blue box and Tobias regaining his morphing ability.
* WonderfulLife: Partially subverted. In ''Back to Before'', the Drode asks Jake if he wants the war taken away. Jake, in a moment of weakness, accepts. What happens? [[spoiler:The Yeerks still invade. A lonely Tobias joins The Sharing, is infested, and later killed when Visser Three discovers the Yeerk infesting him is a spy. Ax, after escaping from the wreck of the Andalite ship, informs the world of the existence of aliens. The Yeerks, in turn, start a full-on military invasion, and Marco, Rachel, and Cassie are killed in short order. Jake and Ax kill Visser Three and claim the Blade ship. They intend to crash it into the Pool ship, but time starts to unravel and the Drode and Ellimist stop everything and revert the situation to normal. The subversion is that, in the WonderfulLife timeline, they actually defeat the Yeerks much ''quicker''; it takes less than a month and a half after Elfangor's death. The 54-book main series is eventually revealed to have taken place over ''three years.'']]
* WorldInTheSky: The Ketrans' homeworld (Ket) in the Ellimist Chronicles.
* TheWorldIsJustAwesome: In #5, when the Animorphs are in space, they look back on Earth and comment that it's beautiful. In #7, the Ellimist shows them scenes of Earth, and says the same.
** In #11 there's a moment where Ax sees all the glories of the rainforest in jaguar morph and says, "Your planet is amazing. Amazing."
* WrittenByTheWinners: Interestingly, it's the humans that do this, [[spoiler:refusing to put Jake on trial for war crimes while happily trying Visser One for the same charge.]]
* WriteWhoYouKnow: Applegate and Grant based most of the characters on people they knew. Applegate has said that the character Loren is based on herself. Grant is described as a lot like Marco but it's unknown if this was intentional (probably more of an author projection thing seeing as Marco's got an {{Expy}} in Grant's series).
** Applegate also said Cassie was most like her, while Marco was most like Michael Grant.
* WriterOnBoard: The ghost-written book "The Experiment" is a heavy-handed anti-meat screed, so much that Applegate stepped in to rewrite the final chapter so that the Animorphs are happily chowing down on hamburgers as a {{Take That}} to the real author. Though Applegate herself doesn't have much room to throw stones, as "The Secret" is just as much of an excuse to rant about the logging industry.
* XanatosSpeedChess: The final battle eventually breaks down into this, as [[spoiler:the kids run around the ship wreaking havoc and looking for any edge to save Rachel, and Visser One (unsuccessfully) attempts to contain the situation]].
* YeGoodeOldeDays: Averted in ''Elfangor's Secret.''
* YankTheDogsChain: Tobias' distant cousin has flown in from Africa and wants to take care of him. He can finally have a real family, stop eating roadkill and have a proper relationship with Rachel. He can have a normal life! ''This is awesome!'' [[spoiler:No, it's not. That cousin is Visser Three. In morph. He's trying to kill him.]]
* YouAreGrounded: Stops being an issue after #25, when the Chee start impersonating the kids whenever they have to go away for long periods of time.
* YouAreNotAlone: A big thing, but most obvious in #31, when Jake's father is at risk of being infested. Jake's panicking and on the verge of having a mental breakdown, and is expecting a longwinded lecture from Marco about the importance of staying clearheaded and rational, instead of doing something stupid and reckless. But Marco just says, "[[CrowningMomentOfHeartwarming You're not alone, man.]]"
* YouAreNumberSix: All Yeerk names and ranks have numbers attached.
* YouCanNotGraspTheTrueForm: The Ellimist.
* YouCantGoHomeAgain: Ax tries to get home early on, but then decides it's better to help out on Earth and wait until the Andalites arrive.
* YouDidTheRightThing: Twice, after the war. Jake's most heinous act by far was [[spoiler:flushing the Pool ship's pool into space, which killed approximately seventeen thousand unhosted Yeerks.]] After the battle, Cassie meets with Erek, who is shocked and disgusted that Jake would do such a thing. Defending Jake, Cassie heatedly replies that Jake "did what he had to do":
--->[[spoiler:'''''Erek''': I see. He feels guilty.\\
'''Cassie''': No. Not guilty.\\
'''Erek''': Then what?! He used me, blackmailed me, manipulated my programming to get me to crack the engine systems and take control of the ship.\\
'''Cassie''': You drained the Dracon beams.\\
'''Erek''': What did Jake expect me to do? I had given him control when he needed it. I wasn't going to enable him to kill.\\
'''Cassie''': Jake had Rachel with Tom. Rachel and Tom are both... And the ship got away anyway. Thanks to you.\\
'''Erek''': And I'm supposed to feel regret because Jake ordered his cousin to take out his brother and I wasn't going to let him kill everyone else on the Blade ship?! So, you too, huh Cassie?\\
'''Cassie''': Jake did what he had to do.\\
'''Erek''': Did he? Somebody flushed the onboard pool into space. Did he have to do that too? They were unhosted Yeerks. They were ''harmless''!\\
'''Cassie''': We needed a div -\\
'''Erek''': A what? A what did you need? A ''diversion''?! You're telling me you needed a diversion so Jake massacred seventeen thousand sentient creatures?! A ''diversion''?!]]
** Similarly, during the war crimes trial of Visser One, one of the Visser's defense lawyers says that Jake himself should be under indictment as a war criminal for his actions. Jake, who has been clinically depressed for some time due to guilt, is cut deeply by this remark. Cassie, Marco and Ax later tell him that his actions were, if not wholly moral, were completely necessary; furthermore, Cassie makes the case that "you can't equate the victim and the perpetrator" when it comes to war crimes.
*** The book itself leaves things a bit more up to reader interpretation, and it's obvious that the characters saying so were significantly less sure of what they were saying than they would like to be.
* YouHaveFailedMe: The BigBad, Visser Three, was notorious for doing this on a regular basis. One Yeerk scientist actually preferred slow death by Kandrona starvation to what Visser Three would do to him.
* YouNoTakeCandle: The Hork-Bajir. [[JustifiedTrope Justified]] because the Arn genetically engineered them not to be very bright. A Hork-Bajir with genius-level intelligence is the result of a genetic mutation the Arn never quite managed to obliterate.
** Even when they're being Controlled, a quirk of the brain causes them to trade languages around. (Gafrash!)
* YouRebelScum: "Yeerk filth!" "Andalite scum!"
* YourTerroristsAreOurFreedomFighters: A major theme of the book, with [[{{Anvilicious}} many an anvil dropped]].
* YourWorstNightmare
[[/folder]]

* ShapeshifterModeLock: More than two hours in a morph traps you in that body. [[spoiler:There are an alarmingly large number of characters who fall prey to this fate - Tobias, Elfangor, David, Aldrea, Aftran, Menderash, the ENTIRE TAXXON RACE, and temporarily Cassie.]]

* GodwinsLawOfTimeTravel: Subversion: Visser Four rockets through the time stream, altering the results of battle to see to it that the human race is more cowed and easier to enslave. He goes to D-Day to ensure a Nazi victory, but [[spoiler:thanks to his previous changes, there aren't any Nazis.]]
** [[spoiler:But they do see Hitler. Though tempted, nobody does anything to him since ''this'' Hitler is just a scared guy driving a jeep.]]
*** Then [[spoiler:Tobias's Hork-Bajir blade either slips or "slips." The question of which it was kinda hangs there unstated.]]

* BizarroEpisode: Cassie has an entire book that's one, ''The Hidden''. A random buffalo somehow acquires morphing powers as the Yeerks cause trouble with Helmacron technology. It's as bad as it sounds.
** ''Megamorphs 2: In The Time of The Dinosaurs'': [[ILoveNuclearPower A nuclear sub explodes, tearing a hole in space-time]] that sends all the Animorphs to the time of the dinosaurs. They meet [[AncientAstronauts the Nesk and the Mercora species]], getting caught in the war between the two. For reasons never explained, morphing won't heal Tobias's broken wing in this adventure. The K-T extinction comet arrives and kills all the dinos and aliens, as well as rocketing the Animorphs back to their own time. After this adventure, the Animorphs find they can not morph into their acquired dinosaur forms.
** ''The Forgotten'' also counts, for similar reasons. In fact, any book written with the ''Sario Rip'' effect is pretty much an instant candidate for a BizarroEpisode.
** ''The Return'' makes absolutely no sense at all. In terms of plotting, it's basically MyImmortal, only published. (It's not quite as bad in terms of writing, although it's not really great.)
** A lot of the ghost written books were this, tending to have plots that were strange even by the standards of the series and deliberately written to have no impact on the larger story.

* EverythingsWorseWithBears: Rachel, always on the edge between ActionGirl and BloodKnight, loves her grizzly morph. The characters consider their polar bear morphs to be their most dangerous, with good reason. [[spoiler:Rachel was killed by a Yeerk in polar bear morph.]]
* [[EverythingsEvenWorseWithSharks Everything's Worse With Sharks]]: And Controller sharks, well, that's just ''awful''.

** Rachel's favorite battle morphs are [[EverythingIsWorseWithBears grizzly bear]] and [[WarElephants elephant]], neither of which is particularly subtle or defensive.

* CoveredInMud: At one point, Cassie jokes about how Rachel never seems to get dirty - that any mud just seems to be deflected away. She throws a ball of mud at Rachel, who knocks it away without it splattering all over her. Cassie comments that Rachel's hand probably isn't even muddy, but Rachel refuses to show her.

* SomebodyElsesProblem: Initially, the kids see the Yeerk war as strictly between the Andalites and the Yeerks, which is why Marco is so against getting involved. However, when Jake learns Tom is a Controller, the kids realize that the stakes are much closer to home than previously thought. By the end of the series, the kids have lost their faith in the erstwhile Andalite reinforcements, and have concluded that it's [[AllUpToYou all up to them]].

* SenseFreak: Ax in human morph, as Andalites are mouthless ("Cinnamon BUNZAH!!!").

* FramingDevice: All of the ''Chronicles'' books. ''The Andalite Chronicles'' is presented as Elfangor's last testament (known by Andalites as a ''hirac delest''), given in the final moments of his life. ''The Hork-Bajir Chronicles'' is told to Tobias by Jara Hamee sometime between books 13 and 23. ''Visser'' has, by far, the most in-depth one, switching back and forth between Visser One's memories and her present-day trial. Finally, ''The Ellimist Chronicles'' is narrated to a then-unnamed dying Animorph, indicating that at least one of them will be KilledOffForReal.

* KilledOffForReal: [[spoiler:The original Visser One (Edriss), Jara Hamee, Rachel, Tom, the Auxiliary Animorphs]].

* AliensStealCable: And record every channel! The Andalites apparently show TV programs like the news and MTV in school as part of learning about humans.

* SlidingScaleOfAntiHeroes: Although the Animorphs spend most of the series somewhere in between type 1 and type 2, [[spoiler:Jake]] dives straight into type 4 during the last 2 books.

* AssPull: [[spoiler: In ''The Departure'', we suddenly learn that metamorphosis resets the morphing clock, meaning that as soon as Cassie became a butterfly, she was no longer a nothlit. This was never mentioned before or after that book.]]

* IdiotPlot: Falls into this sometimes.
** The entire plot with Tom being a controller is an idiot plot. Literally any time they wanted to, the Animorphs could lock him up for three days and pretend that he got lost. This NEVER HAPPENS.
*** They could also win the war pretty quickly by applying this on a larger scale.
**** Only they would then promptly reinfest Tom or kill him to keep him quiet unless he then disappeared. Why they didn't fake his death and then lock him up for three days and smuggle him within the Free Hork-Bajir community or something is a good question though.
** ''The Conspiracy'' has been criticized for being an idiot plot, both on the part of the yeerks and the Animorphs.
** ''The Answer'' has had similar criticisms.
** The recurring plot with the Yeerk Peace Movement can also be taken as an idiot plot, in that the Yeerks could always infest animals that weren't sentient, as proved in ''The Unknown''.
** Also, ''The Hork-Bajir'' chronicles has a small element of this, because the Arn never think to create quickly-reproducing bodies for the Yeerks to infest.

* WhatDoYouMeanItsForKids: In recent years, the books have had a relatively large following with adults who read the series as kids. Some adults are just now discovering it, without knowing that it was intended for children. It's not hard to see why - it's ''incredibly'' dark and violent, and there are some concepts (such as drug abuse) subtly (or not-so-subtly) presented in the text that a kid simply wouldn't get.

* HannibalLecture: Tobias uses this while Taylor is torturing him. * HappyPlace: When Taylor figures out that simply torturing Tobias won't work, she starts sending him to his HappyPlace too, attempting to shatter his mind by jumping from pure pleasure to pure pain. [[spoiler:It works, but Taylor is too far gone herself to notice.]]
** Although interestingly enough, you could also argue that she tries this method specifically because Tobias is sending HIMSELF to a Happy Place (albeit not a terribly happy one) in order to keep from breaking down. Up until that point, he'd been surviving Taylor's methods by hiding in the hawk half of his mind, which, being the brain of a wild animal, was much better at living with pain without suffering deep psychological damage than his human side was. That's why the Happy Place method was so effective- the hawk brain was good at dealing with pain, but it didn't know what to do with happiness, which isn't something that a hawk brain understands. The happiness was just too tempting for Tobias' human side, and it drew it out of hiding- at which point Taylor slammed down on the pain button again and wacky fun ensued.

* GodForADay: Rachel was given the chance to become the ultimate fighting machine by Crayak. However such things are not much fun for a Blood Knight and it leaves only the satisfaction of sadistically snuffing out your enemies which is a road she doesn't feel comfortably going down when Crayak starting saying she is Not So Different.

* GambitPileup: In Book #53 The Answer, [[spoiler: Jake uses the auxiliary Animorphs, and the U.S. National Guard to distract Visser Three, so he can sneak above the Pool Ship. Or so Visser Three thinks. Actually, Jake is relying on him to believe that, so he doesn't realize that Jake and the other Animorphs are '''already''' aboard the ship, with help from Tom, who wants Visser Three dead himself, and plan on fighting him with the help of the free Taxxons. '''But''', Tom decides to betray Jake to Visser Three at the last moment, which Jake saw coming and avoided dying with help from the Chee, who Tom and Visser Three didn't even know existed. Yeah.

* SkippyRules: The Law of Seerow's Kindness.