History Main / EvilMakesYouMonstrous

* ''WesternAnimation/PhineasAndFerb'': In "[[Recap/PhineasAndFerbThisIsYourBackstory This is Your Backstory]]", [[Characters/PhineasAndFerbHeinzDoofenshmirtz Heinz Doofenshmirtz]] succeeds in getting enough of his backstories to make him more evil, which turns him into a monster.

** ''TabletopGame/PrometheanTheCreated'': Usually driven over the DespairEventHorizon by the raft of crap Prometheans have to deal with, the Centimani turn their back on [[ToBecomeHuman the Pilgrimage]] and start dealing with [[TheDarkSide Flux]]. This usually results in mutations. ''Lots'' of mutations.

** Hypocrites become ghouls (female SkyPirates in this setting).

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[[quoteright:350:[[VideoGame/DawnOfTheDragons https://static.tvtropes.org/pmwiki/pub/images/unholy_rite_dawnofthedragons.png]]]]
[[caption-width-right:350:At last, a visage to match the growing horror within.]]

Characters who decide to [[JumpingOffTheSlipperySlope toboggan]] down [[TheDarkSide The Dark Slide]] will have a fun time of it... at first. It starts small, maybe an EvilMakeover with SpikesOfVillainy and RedRightHand. But there's a nasty surprise at the bottom of this insidious slide; those who commit especially heinous crimes, abandon all of their humanity for power, or allow their inner darkness to bloom into a blight won't just grow [[CuteLittleFangs tiny]] [[FangsAreEvil fangs]] or discover EvilMakesYouUgly, they'll find out [[TitleDrop Evil Makes You Monstrous.]]

This is usually a feature of legends, both in real life and in stories. Basically, a guy, gal or even animal becomes so mean, malicious, and generally '''''Evil''''' that they transcend their mortal existence and become a monster of legend. A scourge on man and beast. After killing enough, the SerialKiller goes from a man into a force of nature that [[HealingFactor just]]. [[ImplacableMan Won't]]. ''[[BackFromTheDead Die.]]'' The [[WickedWitch witch]] buried in the heart of the woods will rise from her grave and haunt it as a [[OurLichesAreDifferent half-dead corpse]] until her [[SoulJar spellbook is destroyed]]. The man who killed and ate his family out of hunger transforms into a {{Wendigo}}. The CreepyChild [[BullyingADragon everyone picks on]] lets the hatred fester and ferment until she becomes a living poltergeist. The devil worshipper so taints their souls that they [[DemonOfHumanOrigin transform into a demon]].

* ''Anime/DragonBallSuper'': During Fused Zamasu's fight against the heroes, his wonky HealingFactor means that as he takes hits, he mutates into a large purple monster as he takes more damage. Gowasu theorizes that it's his inner evil now manifesting on the outside, showing just how far he'd fallen in the pursuit of his warped ideals. [[spoiler: His final form, Infinite Zamasu, is ''even worse'', since he has essentially become the multiverse at this point and appears as dozens of Zamasu faces in the sky.]]
* The evil humans fought by the DWMA in ''Manga/SoulEater'' are often incredibly bizarre. In the anime it's stated to be because eating humans souls was turning them into Kishin, whereas in the manga only weapons can eat souls, leaving their strangeness more or less inexplicable.
* ''Manga/WolfGuyWolfenCrest'': When [[spoiler:Chiba]] is taken over by his bloodlust and obsession with killing Haguro, he becomes a [[NightmareFace deformed ogre]] instead of a werewolf.
* ''Manga/{{Berserk}}'' has the [[EldritchAbomination Apostles]], every one of whom WasOnceAMan (or woman, or child) before making their sacrifice to the Godhand and being reborn as demons, usually with a heaping helping of BodyHorror to go with their new superpowers. ZigZagged by [[spoiler:Griffith, who becomes slightly monstrous upon transforming into Femto, only to cross the BishonenLine and emerge even ''more'' beautiful after being reborn into the physical plane. This is because [[DemonLordsAndArchdevils the God-Hand]] get to choose their own form, and Griffith was a rather vain person in life.]]

* [[spoiler:The Witches]] in ''Anime/PuellaMagiMadokaMagica'' are [[spoiler:former magical girls who have succumbed to the curses resulting from their wishes. While as magical girls they still look fully human, as witches they become bizarre monsters in a world of AlienGeometries]].

* ComicBook/{{Wendigo}}, particularly the Creator/MarvelComics version. (Only 98% though -- the rabid man turns into Wendigo more or less permanently, not only on the anniversary.)
* In one issue of the [[ComicBook/TheLegendOfZelda Valiant Zelda comics]] Link steals the Triforce of Power from Ganon. As a result he [[WithGreatPowerComesGreatInsanity starts turning evil]], and nearly completely transforms into a piglike monster similar to Ganon.

* Marvel villain ComicBook/TheHood has a red hooded cape that gives him magic powers -- and is warping him into a demon.
* ''ComicBook/StarWarsLegacy'' Darth Krayt's own Vonduun Crab Armor(Yuuzhan Vong armor) has completely fused with his skin.
* Assuming that ComicBook/TheJoker started out as an ordinary man, whatever turned him into a Monster Clown certainly has this trope happen to him. However, in ''ComicBook/DeathOfTheFamily'', he has successfully outdone himself by first having his face removed, and then coming back one year later to wear it like a mask. Now he looks like a villain out of a SlasherMovie.
* ''ComicBook/JudgeDredd'': Dredd's nemesis Judge Death, a walking corpse who believes that life is a crime, was once a human being in an AlternateUniverse. Death spent his whole life killing people before allowing a pair of witches to turn him and his three lieutenants into undead abominations to achieve immortality. Since he was already pure evil long before his transformation, casting off the last of his humanity means the outside simply started to reflect the inside.
* ''ComicBook/NemesisTheWarlock'': After [[ANaziByAnyOtherName Torquemada]] was killed by Nemesis in a TeleporterAccident, he returned as a monstrous, distorted, clawed phantom who had to [[DemonicPossession possess rapidly-decaying hosts]] to interact with the physical world effectively.
* ''ComicBook/RequiemChevalierVampire'': A literal take, where people are turned into various monsters in the afterlife based on their sins in life:
** Religious fanatics become werewolves;
** Infanticidal women become harpies;
** Rapists become centaurs;
** Hypocrites become ghouls (female SkyPirates in this verse);
** {{Mad Scientist}}s become Archeologists, continuing their sick experiments and having to wear newly-flayed skins;
** Vampires are a more eclectic bunch (basically comprising everyone who committed evil for sadistic reasons), including Vlad Tepes, Attila the Hun, Alister Crowley, several Nazis, a Japanese participant in the Rape of Nanking, Maximilien Robespierre and Nero;
** People who committed evil in the name of empires (mostly British colonialists) become LizardFolk (led by the dragon Myth/KingArthur);
** Victims of evil either become zombies (seems mostly to apply to soldiers who fought in pointless wars) or lemures (ghosts that only move when their tormentor in life is expired on Résurection);
** [[spoiler:Hitler]] was somehow prevented from turning into anything, instead kept as a safety measure against the six million or so Lemures that passed on with his neck being snapped by Dracula.

[[folder:Fanfic]]
* In ''Fanfic/ThousandShinji'' the main characters become worshippers of the ''TabletopGame/{{Warhammer 40000}}'' Chaos Gods. Their dark gods' gifts gradually mutate their bodies until Asuka becomes a red-skinned, bronze-haired, muscled demon, and Rei looks like a diseased, rotten living corpse.
* In ''WesternAnimation/TheBlackCauldron'' fic ''Fanfic/HopeForTheHeartless'', the [[OurLichesAreDifferent Horned King]] is revealed to [[WasOnceAMan have been a human]] who became what he is today centuries ago when he lost his [[AnatomyOfTheSoul heart and humanity]] with the numerous atrocities he committed in the name of [[EvilMentor his master Arawn]] and later in his own name after his master was vanquished.
-->'''The Horned King''': The heart is the messenger from the soul to the body, and keeps the two bound together as one. When the body fails, the heart ceases to be, and the soul is released from the body and sent elsewhere. You can see this in your elderly, however there is another scenario. After killing someone, the heart, the origin of all morality and emotion, begins to corrode. Slowly, but it is noticeable. [[SlowlySlippingIntoEvil The more one kills, the more difficult the damage is to reverse.]] [...] After one has killed so much that the heart is gone and no longer holds the life in them, they begin to decay on the outside as well, as the heart binds the body and soul together, and without the heart, the soul cannot function properly. You see this with anyone who has killed before. They are alive, but they are not, and their outward appearance begins to reflect what they have become on the inside, and [[WalkingWasteland what they leave in their wake]]. I look like this because I am the embodiment of all that I have become. My heart turned to dust centuries ago, taking all life with it, and left me merely in a state of existence, my soul unable to work properly without it, thus my appearance.

* Ludmilla, the [[EvilChancellor Tsar's advisor]] in ''WesternAnimation/BartokTheMagnificent'', steals and drinks a potion that transforms anyone into "ten times what they are on the inside." She thinks it'll [[ObliviouslyEvil make her ten times more beautiful]], but it instead transforms her into a [[ScaledUp giant ugly purple dragon]].

[[folder:Films -- Live Action]]

* Freddy Krueger of ''Franchise/ANightmareOnElmStreet'' somehow managed to become an undead dream-dwelling humanoid monster just by being ''really'' nasty to kids. The [[Film/FreddysDeadTheFinalNightmare sixth film]] reveals that he was given his powers upon dying by several nightmare demons.
* ''Franchise/{{Halloween}}'s'' Michael Myers went from a [[SuperStrength super-strong]], [[TheSociopath sociopathic]] human with plans to kill his sister to a [[JokerImmunity completely unkillable supernatural being]] hell-bent on massacring half of Haddonfield. And if you follow [[Film/HalloweenTheCurseOfMichaelMyers the sixth movie's]] canon, his power is making him grow bigger in each movie.
* In ''Film/{{Doom}}'', Chromosome 24 turns evil people (or people with a great potential for evil) into monsters and those who aren't into superhumans. [[spoiler:Sarge, who had earlier crossed a moral line but was still just following orders,]] starts out superhuman after being infected but turns into a monster during his fight with Reaper the moment it seems like he's really going to murder him.
* ''Franchise/StarWars'': Darth Vader got all his flesh burned off, all his limbs cut off, and earned a black skull-faced suit. Darth Sidious was disfigured into a withered wrinkled ghoul of a man. [[ArsonMurderAndJaywalking Darth Maul got tattoos all over his body]], his horns and demonic looks on the other hand are just natural to his species. Only Count Dooku got away with his looks and stayed classy.
* Davy Jones from ''Franchise/PiratesOfTheCaribbean'' movies [[Film/PiratesOfTheCaribbeanDeadMansChest two]] and [[Film/PiratesOfTheCaribbeanAtWorldsEnd three]] was supposed to use his supernatural ship, the ''Flying Dutchman'', to transport the souls of those who died at sea to the afterlife. After his lover [[PhysicalGod Calypso]] abandoned him, he in turn abandoned his duties and began instead to bargain for the souls of dying sailors to become part of his undead crew, at which point they would be tortured until becoming one with the ship. This caused him (and, by extension, them) to mutate into horrific amalgamations of human and sea creature.

* According to ''Film/HanselAndGretelWitchHunters'', any woman who turns evil and becomes a witch cannot perfectly hide her rotting flesh to a thorough examiner. Hansel uses it to prove that Mina is not a witch [[spoiler:He turns out to be wrong, but the trope still applies because white witches like Mina are good and remain untarnished]]. Grand Black Witches can take on attractive forms, but when they use their powers they revert to their monstrous form.
* Chucky from the ''Film/ChildsPlay'' movies. Charles Lee Ray was actually a TallDarkAndHandsome man before his death and the voodoo ritual that turned him into a doll, with long hair and a square jaw, albeit criminally insane. The more time he spends in the Good Guy doll, the more evil the doll looks (as well as slowly mutating from plastic to actual flesh and blood).
* Ben Willis, the Fisherman from ''Film/IKnowWhatYouDidLastSummer'', was originally a revenge-driven killer who used a hook as his [[WeaponSpecialization weapon of choice]]. By the time of ''Film/IllAlwaysKnowWhatYouDidLastSummer'' he's apparently become an undead ghost/living memory still driven to kill.
* Dracula in ''Film/BramStokersDracula'' had this happen to him after renouncing god and becoming a vampire. In his default form, he barely looks human, having a major case of UndeathlyPallor. While he can become young, when he lets it slip, his face is shown to be very monstrous and bumpy, implying that his true form. Considering he's shown to become a wolf, werewolf like creature and a bat, it makes sense as the curse is essentially an amalgamation of those creatures.

* This is one of the possible origins of a vampire, according to some accounts.
** And werewolves of the [[ImAHumanitarian cannibalistic]] SerialKiller type.
* This is also common in Myth/NativeAmericanMythology. Many, ''many'' monsters are spawned due to someone acting in such an anti-social fashion for so long that they become monsters.
** In the Native American mythology you may turn into a Wendigo if you become a cannibal.
* Myth/NorseMythology's Fafnir (who, depending on the source, is either a dwarf, a giant, or a man) murders his own father over a pile of gold, then turns into a dragon that constantly guards the treasure (''Literature/PoeticEdda'', ''Literature/ProseEdda'', ''Literature/TheSagaOfTheVolsungs''). While this appears to be a voluntary transformation, Fafnir never shifts out of his dragon shape.

* One of the reasons that God [[TheseAreThingsManWasNotMeanttoKnow prevents us]] [[YouCannotGrasptheTrueForm seeing demons]] is because they are ''so ugly and monstrous'', according to the Christian saints, who were able to see them, ''[[GoMadfromtheRevelation that they could drive us mad]]''.

* Eustace in ''Literature/TheChroniclesOfNarnia'', very allegorically becomes a dragon by being greedy and messing with a [[DragonHoard dragon's hoard]].
* ''Literature/EnchantedForestChronicles'': Waraug the evil dragon in ''Dealing With Dragons'' turns into a frog after displaying un-dragonlike behavior.
* This happened to [[BigBad Lord Voldemort]] from ''Literature/HarryPotter''. He lost his handsome looks and acquired ugly snake-like features after using too much [[BlackMagic Dark Magic]]. He also made himself very, very difficult to kill through the same means.
* Tends to happen to the most powerful Dead in the ''Literature/OldKingdom'' books. The deeper regions of death have strongly metamorphic properties, so that any spirit that forces its way back into the world of the living from there will have to be quite powerful to do so, but will no longer resemble its human form--and ''any'' dead spirit that willingly returns to life is a walking abomination against the natural order and a threat to any living person who encounters it.
* In Creator/EvaIbbotson's children's novel [[Literature/DialAGhost ''Dial A Ghost'']], one of the ways OurGhostsAreDifferent is that evil ghosts decay in appearance over time while good ghosts still look mostly like they did in life. Some of it is apparently based on neglect for personal appearance and/or deliberate attempts to appear scary, but just plain being hateful seems to mess them up pretty well on its own--an unpleasant character seen just after his death is described as being even uglier as a ghost than he was as a man.
* Creator/JRRTolkien was fond of this trope, probably because of his own spiritual beliefs. Orcs, for example, are corrupted versions of Elves turned evil by Morgoth. Many Men serving Sauron eventually turn to be like this, like the MouthOfSauron. Gollum (originally a Hobbit) is another example of a normally good creature turned monstrous from the influence of evil. Sauron himself was originally a beautiful, angelic being and was able to still appear as such (as in his guise of "Annatar"), but after committing more evil and helping to instigate the Fall of Númenor, he lost the ability to ever again appear as anything other than hideous and terrible.

[[folder:Live Action TV]]

* In ''Series/{{Supernatural}}'', Wendigo are created when humans dine on human flesh. The hunger grows and grows until they're nothing but beasts.
* In ''Series/KamenRiderDecade''[='s=] version of ''Series/KamenRiderHibiki'', an [[HenshinHero Oni]] who loses sight of [[ForGreatJustice justice]] and [[BloodKnight fights only to become stronger]] will become a powerful, corrupted, ox-like Makamou called Gyuuki. [[spoiler:This happens to Hibiki, forcing his young student Asumu to MercyKill him and take up the title of Hibiki.]]
** The line between monster and human is a common theme in Rider shows, since a lot of its heroes [[PhlebotinumRebel gained their powers from evil sources before using them for good]].
* ''Series/SamuraiSentaiShinkenger'', being heavily based on Myth/JapaneseMythology, has several bad guys who are explicitly ex-humans who went bad enough to become monsters. The villains for the show are even called Gedoushu, literally "Outside Path Ones", because they have left the path of humanity.

* Fomori in ''TabletopGame/WerewolfTheApocalypse'' tend to be created when the Wyrm warps the flesh of those who are corrupt.
* The ''TabletopGame/ChroniclesOfDarkness'':

** ''TabletopGame/MageTheAwakening'': the Mad are mages who have committed so many heinous acts that their {{Karma Meter}}s bottom out and their [[OurSoulsAreDifferent souls]] shatter, letting their magic start to leak out all over the place and manifest whatever psychoses pushed them over the edge.
** ''TabletopGame/PrometheanTheCreated'': The Centimani. Usually driven over the DespairEventHorizon by the raft of crap Prometheans have to deal with, they turn their back on [[ToBecomeHuman the Pilgrimage]] and start dealing with [[TheDarkSide Flux]]. This usually results in mutations. ''Lots'' of mutations.
** ''TabletopGame/VampireTheRequiem'': The lower a vampire's [[KarmaMeter humanity,]] the less they are able to pass for human. While low-humanity vampires aren't necessarily hideous, they tend to [[UncannyValley seem weird and unnatural to humans,]] and often get pale and corpse-like. Having low humanity also changes a vampire's metaphysical biology to be less human-like, such as requiring them to drink more blood to survive and making them stay in torpors longer.
* In ''TabletopGame/{{Warhammer}}'' and ''TabletopGame/{{Warhammer 40000}}'', worshippers of Chaos will inevitably mutate--sometimes rather quickly--as the power of Chaos seeps into their being. Chaos mutations tend to be rather...grotesque, even horrifying. Eventually, this power will be the key to the apotheosis into a [[EldritchAbomination Daemon]] [[AscendedToAHigherPlaneOfexistence Prince]], although failure or inability to keep the power from overwhelming oneself, leads to succumbing to the mutations and becoming a mindless [[BodyHorror Chaos Spawn]], which is a much more common fate (provided they survived to that point).
** It's implied Doombreed, the oldest Daemon Prince of Khorne, was better known in life as Genghis Khan.
** The Dark Eldar of 40k, though they generally have a somewhat genteel evil look, have [[ScienceIsBad Haemonculi]], who enforce this trope ''on themselves'', with a combination of surgical and quasi-scientific means. One of them CameBackWrong from the dead, and every new death fails to restore him exactly to the previous state, so nowadays cheerfully lets himself be killed just so he can see what changed this time.

** ''TabletopGame/{{Ravenloft}}'' invokes this to the point of having game mechanics for it. Whenever a player character commits an evil act, the DM makes a secret roll to find out if this attracts the attention of the [[PowersThatBe Dark Powers]]. This normally results in gaining a supernatural power and a RedRightHand to go with it. Repeated evil acts lead to further progression down a chart, and a PC who reaches this stage becomes a monstrous NPC Darklord. Some [[MoralEventHorizon "Acts of Ultimate Darkness"]] can automatically take a character to Darklord status.
* In ''TabletopGame/MagicTheGathering'' the planeswalker Ashiok is gradually transforming into something else as they orchestrate acts of evil. Thus far they've transformed about half their head into dark mist and a pair of slender black horns (in the process removing the eyes and brain, which they seem to have passed beyond a need for). Arranging the massacre of an entire city turned a few more specks of their cheek into this mist, indicating that countless atrocities lie behind the progress that's been made so far.
* In ''TabletopGame/{{GURPS}} Fantasy II: The Mad Lands'' the eponymous Mad Lands are so saturated with WildMagic that people who break tribal taboos will eventually transform into monsters corresponding to their specific wrongdoing; for example, greedy or gluttonous people may turn into [[OurVampiresAreDifferent Bloodless]], while those that are metaphysically "thin-skinned", excessively whiny or prickly, may literally lose their skin and become Skinless.
* ''TabletopGame/PrincessTheHopeful'': ZigZagged with the effects of [[TheDarkSide Dark Warping]].
** The majority of Darkened develop [[LovecraftianSuperpower Umbrae]] as they fall further into the Darkness, and when they hit [[KarmaMeter zero Integrity]] they die and a bestial (and totally inhuman) Darkspawn is born from their corpse.
** But on the other side of the coin you have Mnemosynes, those who were already so evil that they welcomed the Darkness in without a fight. As a result, they never developed Umbrae and retained their human bodies and minds. This means that they ''can'' pass for normal when they need to, not to mention being able to use tactics and make long-term plans.

* In the ''Franchise/KingdomHearts'' games, those who choose to become evil often wind up becoming Heartless (and Nobodies if their hearts are strong enough), with their form and power depending on how evil they were at the moment of their deaths. In very rare cases[[note]][[BigBad Terra-Xehanort]] and [[WesternAnimation/TheLionKing1994 Scar]][[/note]], the person retains their original form as a Heartless. This fate would befall to at least six Disney Villains[[note]]Scar, [[WesternAnimation/{{Cinderella}} Lady Tremaine and her two daughters]] (presumably), [[spoiler:[[WesternAnimation/{{Tangled}} Mother Gothel]], and [[WesternAnimation/Frozen2013 Prince Hans]]]][[/note]].
** [[WesternAnimation/SleepingBeauty Maleficent]] also takes on her dragon form at times, including when Ansem, Seeker of Darkness stabs her with a dark Keyblade to unlock the darkness in her heart.
* As Sorceresses in ''VideoGame/FinalFantasyVIII'' grow older and continue to use their magic, their power begins to change their appearance into something less human and more monstrous. [[https://finalfantasy.fandom.com/wiki/Edea_Kramer Edea]] was a fairly young sorceress so her appearance (while slightly altered) was still beautiful, whereas the older (and far crueler) sorceress [[http://finalfantasy.wikia.com/wiki/Adel Adel]] had morphed into a monstrous, muscular being. However, Sorceress [[http://finalfantasy.wikia.com/wiki/Ultimecia_%28Boss%29 Ultimecia's]] appearance is up for debate - her true form might be that of a winged, scantily clad woman, or her true form might actually be her barely human existence-sucking [[OneWingedAngel final]] [[http://finalfantasy.wikia.com/wiki/Ultimecia_(final_boss) form]]. Considering how the other sorceresses look, the latter is more likely.
** Then there are the various sorceresses the player must fight during Time Compression. The [[http://finalfantasy.wikia.com/wiki/Sorceress_%281%29 first batch]] have odd skin colors and facial markings but still resemble beautiful women, the [[http://finalfantasy.wikia.com/wiki/Sorceress_%282%29 second batch]] look a little less human and have eerily [[EvilLaugh warped laughs]], while the [[http://finalfantasy.wikia.com/wiki/Sorceress_%283%29 final sorceress]] resembles a fat, bloated, purple slug.
* In ''VideoGame/FinalFantasyX'', this is how [[spoiler:one of Yevon's monks was turned into Omega Weapon]].
* ''Franchise/TheLegendOfZelda'': When Ganondorf made his wish on the Triforce in ''VideoGame/TheLegendOfZeldaOcarinaOfTime'', it transformed him into a monstrous Pig Man known as Ganon, seen in ''[[VideoGame/TheLegendOfZeldaALinkToThePast A Link to the Past]]'' and [[VideoGame/TheLegendOfZeldaI other]] [[VideoGame/ZeldaIITheAdventureOfLink games]], to reflect his greedy nature. Although he is sometimes able to revert back to his human form at will, he definitely received the absolute refusal to actually stay down.

* In ''VideoGame/ChronoTrigger'', [[spoiler:you'd never know that Fiendlord Magus and Prince Janus were one in the same by looking at them. Considering his hatred for Lavos and goals for {{Revenge}} over a 20 year timespan, the Prince's appearance became twisted as he took on the role of the Fiendlord. As Janus, he had a light complexion, light blue hair, green eyes, eyebrows, and round ears. As Magus, he now has a pale gray complexion, dark blue hair, [[RedEyesTakeWarning red eyes]], NoBrows, and PointyEars.]]
* In ''VideoGame/DiabloII'', the protagonist from ''VideoGame/Diablo1997'', after defeating the eponymous Demon Lord, put his soulstone into his own body in an attempt to contain his evil. As the game progress, Diablo takes over his body, gradually making him more monstrous until he turns back into the [[OneWingedAngel hideous]] [[EldritchAbomination Demon form]] Diablo used to assume.

* In ''VideoGame/LiveALive'', this is the fate of [[spoiler:the knight Oersted]]. Originally one of the most straight up heroic player characters in the game, he [[FallenHero falls]] after he is betrayed and abandoned by everyone he knows. After accepting the mantle of "Lord of Dark", he seems to prefer his new monstrous form to his original appearance. [[spoiler:He reverts to his original human appearance right before he [[DeathEqualsRedemption dies while warning the other heroes not to repeat his mistakes.]]]]
* ''VideoGame/TheElderScrollsVSkyrim'': Vampirism. A bite from a vampire will cause you to contract the disease that turns you into one but you have three days to cure it before you actually become one. So pretty much all vampires in Skyrim are vampires by choice.
* Isamu in ''VideoGame/ShinMegamiTenseiIIINocturne''. He decides to seek the truth by himself, not accepting ''any'' help... and next time you see him, [[spoiler:he's absorbing countless stray spirits in the Amala Network to empower himself]]. Result? [[spoiler:He ends up with ''dozens'' of faces growing out of his body]].
* Ryu from the ''Franchise/StreetFighter'' series has an evil form, cleverly named "Evil Ryu". In the series, it is said that those who train in the art of Ansatsuken (Ryu's fighting style), they can tap into even more power with Satsui no Hadou, which causes the user to do anything for victory, including murder. Ryu using this power is what gave series boss Sagat, a gaping scar across his chest for sequels to come.

* ''[[{{VideoGame/OFF}} OFF]]'' plays this one straight with [[spoiler: [[VillainProtagonist The Batter.]]]] [[MindScrew May]][[RuleOfPerception be.]]
* In the ''Videogame/{{Fable}}'' series, your character's appearance is affected by your [[KarmaMeter moral standing]], with evil characters developing glowing eyes, pale skin and even horns.
* ''VideoGame/MetalGearSolidVThePhantomPain'': Due to the hidden "Demon Points" counter, every immoral action Snake commits (killing animals or enemy soldiers, attacking your buddies, killing Diamond Dogs staff, developing nukes, etc.) will slowly cause this to happen to him. At 20,000 points, his shrapnel horn grows significantly to resemble an actual horn, and at 50,000 points, it grows even longer and Snake [[BloodIsTheNewBlack becomes permanently covered in blood]], becoming a true demon.
* ''VideoGame/ResidentEvil6'': [[spoiler: Carla Radames]] infects Simmons with the C-Virus with this very trope in mind:
-->"At first, you'll be afraid. But don't worry. You're just becoming the monster you ''always'' were."
* In ''VideoGame/UntilDawn'', [[spoiler:true to Algonquian mythology, the act of [[ImAHumanitarian eating human flesh]] transforms a person into a monstrous {{Wendigo}}, an undead predator with lanky arms and vicious teeth. The mountain the protagonists have visited has been infested with them since 1952 when [[NoPartyLikeADonnerParty a bunch of miners resorted to cannibalism to survive after being trapped for weeks by a cave-in]]. The survivors were transported to a sanatorium where they transformed, massacred the nurses and other patients and fled into the night. Years later, when Hannah and Beth fell off a cliff resulting in the latter's death, the former's maiming and both being presumed dead, Hannah resorted to eating her sister's remains, transforming her into the fearsome Makkapitew.]]
* Arguably this happens in ''VideoGame/ShadowOfTheColossus'', as [[spoiler:killing the colossi gradually turns the protagonist into a monster.]]
* ''Videogame/{{Undertale}}'''s Genocide Run downplays this in a way that's still terrifying, in that the child's sprite never changes, but their ''behavior'' does, and it seems their appearance changes in ways visible to other characters but not expressible in the artwork. Sans and Papyrus note that they don't emote (their sprite has a never-changing expression, but this is different), stare creepily, and shamble about covered in dust (i.e. monster remains- basically, it's fantastic BloodIsTheNewBlack). Other [=NPC=]'s become terrified of them when they get close to them, including Doggo, a character that's nearly blind, who remarks that he can't stop shivering when the child approaches. The kid also keeps walking through Papyrus's puzzles and the speeches of various characters, which both unsettles them and ticks them off. But the real kicker comes right after the introduction of Sans and Papyrus. Sans tells the kid that his brother would really love to see a human, and asks them to keep ''pretending to be one''. That's right, you've become so evil and twisted, ''you don't even register as human anymore!'' Heck, even ASGORE, a monster who has seen and interacted with humans before, is unable to tell that you are one because of how drastically you have changed.
-->'''Asgore''': Hmm... what kind of monster are you? I'm sorry, I cannot tell...
* ''VideoGame/MortalKombat2011'': Near the climax, Liu Kang, who has become disillusioned with the mounting body count as a direct result of Raiden's actions, attempts to attack the thunder god. Raiden is forced to defeat Liu Kang in combat to prevent him from interfering, causing Liu Kang to get severely wounded when Raiden's electricity reacts with Liu Kang's fireball and incinerates him. A horrified Raiden begs the mortally wounded Liu Kang to forgive him, but Liu Kang refuses. A similar thing happens to Kitana in ''MKX'', as when she is revived as a revenant after being killed off by a brainwashed Sindel, she notes that Raiden doomed her to the Netherrealm. In ''VideoGame/MortalKombatX'', Liu Kang and Kitana's souls were collected by Quan Chi, who used it to create [[ReforgedIntoAMinion evil "revenant" versions]] of the fallen Shaolin monk and Edenian princess. Liu Kang and Kitana ''actually'' [[EvilFeelsGood feel better committing evil deeds]] due to the immense hatred they hold towards the thunder god they once considered an ally, and decide to become the CoDragons to Quan Chi and Shinnok. [[spoiler:After Quan Chi is KilledOffForReal by Scorpion and Raiden condemns Shinnok to a FateWorseThanDeath, [[DragonAscendant Liu Kang and Kitana]] even become the [[HellHasNewManagement new co-rulers]] [[TheEmperor of the Netherrealm]].]]
* In ''Videogame/WarCraft'' ''III'', Illidan absorbs the power of the Skull of Gul'dan at Arthas' suggestion, turning himself into a powerful and monstrous looking demonic being. When Arthas and Illidan clash in the final mission of the ''Frozen Throne'' expansion, Arthas mocks him for this.

* In ''WebAnimation/BabushkaTheMovie'', the events of a famous round of ''VideoGame/AmongUs'' are depicted, and the more that the impostors LetsPlay/{{Valkyrae}} and Creator/{{Sykkuno}} kill, the more inhuman and demonic their appearance becomes. They look normal up until their second kills, at which point both briefly gain BlackEyesOfEvil with HellishPupils, although this only last lasts a second, and Sykkuno briefly has [[RedEyesTakeWarning scary-looking red eyes]] for a few seconds just before his second kill. After Rae kills someone for the third time, her black eyes become permanent and at least from some angles, it looks like she has fangs as well. See the video [[https://www.youtube.com/watch?v=3JmGQTMvO-U here.]]

[[folder:Web Original]]
* ''Podcast/AliceIsntDead'': [[spoiler:It turns out that this is the origin of the thistle men. When people commit extremely evil deeds, good people comfort themselves by believing those people are monsters and not people. This belief is so strong that it actually became true and caused monstrously evil people to be warped into literal monsters.]]

[[folder:Web Comics]]
* Kavonn of ''Webcomic/CharbyTheVampirate'' curses [=LaBelle=] so that cruel actions on her part will physically alter her to be more "ugly", which eventually makes her a giant monstrous wolf.
* ''Webcomic/ElGoonishShive'': Aberrations, the local version of vampires. You can't become one accidentally, you have to deliberately choose to become one, and becoming one means that you lose all human empathy and must prey on humans to extend your lifespan. All aberrations also have an inhuman form which they must be in to feed or to access their full power, though some aberrations retain the ability to assume a human form as a disguise.
[[/folder]]

* Gibson from ''WesternAnimation/SuperRobotMonkeyTeamHyperforceGo'' when he's infected with TheVirus in the episode "Thingy".
* Though it's revealed in ''Luna Eclipsed'' of ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' that [[Characters/FriendshipIsMagicPrincessLuna Princess Luna]] can change to her [[SuperpoweredEvilSide Nightmare Moon]] appearance whenever she wants, it was still her preferred and default form when she [[FaceHeelTurn turned evil]].

** In his first appearance, the {{sociopath}}ic [[CorruptCorporateExecutive industrialist]] [[BigBad Derek Powers]] is revealed to have produced a deadly biochemical weapon to sell overseas. He ends up [[HoistByHisOwnPetard getting exposed to some of the poison gas himself]]. After receiving emergency radiation therapy, he turns into Blight, a [[AtomicSuperpower radioactive]] supervillain who looks like a [[SicklyGreenGlow glowing green skeleton]]. Now his appearance really matches his inner self.

* In ''WesternAnimation/HeManAndTheMastersOfTheUniverse2021'', the power of [[TheDarkSide Havoc]] mutates those who embrace it into monstrous forms that reflect [[PersonalityPower the worst aspect of a person.]] Prince Keldor was cursed with Havoc when he tried to steal the power of Grayskull, but eventually welcomes the power and stabilizes into Skeletor. He then sets out to master and empower those loyal to him with "the purity of Havoc" to create his Dark Masters.
* ''WesternAnimation/TeenageMutantNinjaTurtles2012'': When Shredder mutates into the [[Characters/TeenageMutantNinjaTurtles2012TheShredder Super-Shredder]] in late Season 4, he turns into a freakish being with spikes, and his sanity continues to go downhill. He also abandons his affection for Karai in "Requiem" and leaves her to die in a burning building; on top of that, he has seemingly abandoned his love for Tang Shen, which was [[LoveMakesYouEvil his former driving motivation for going after Splinter]], declaring that it's fitting that Karai should die in the same manner as her mother. Both Karai and Splinter even lampshade it, declaring that Shredder is now a monster both inside ''and'' out.
* ''Franchise/Ben10'' has this as the motif for Kevin in the original series with his reckless use and absorption of Ben's alien causing him to mutate into a amalgamated monster with parts of various aliens he had absorbed from Ben. Ben himself lampshades this telling Kevin he had always been a freak, but now the ugly is on the outside.
* The [[BigBad Big Bad]] from ''WesternAnimation/TheOwlHouse'', [[Characters/TheOwlHouseEmperorBelos Emperor Belos]], [[spoiler:originally started as an ordinary human named Philip Wittebane, but after developing an affliction during his stay on the Boiling Isles by trying to carve glyphs into his arms to try to control the magic, he begins to consume Palismen souls to keep himself alive, this inevitably leads to him mutating into a twelve foot tall, skeletal monster made of rotting, liquefied flesh, that is absolutely covered in glowing blue eyes. The Collector even suggests that ''this is now his true form''.]]
* ''WesternAnimation/PhineasAndFerb'': In "This is Your Backstory", [[Characters/PhineasAndFerbHeinzDoofenshmirtz Heinz Doofenshmirtz]] succeeds in getting enough of his backstories to make him more evil, and it turns him into a monster!

* Though it's revealed in ''Luna Eclipsed'' of ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' that [[DarkIsNotEvil Princess Luna]] can change to her [[SuperpoweredEvilSide Nightmare Moon]] appearance whenever she wants, it was still her preferred and default form when she [[FaceHeelTurn turned evil]].

* ''WesternAnimation/TeenageMutantNinjaTurtles2012'': When Shredder mutates into the Super-Shredder in late Season 4, he turns into a freakish being with spikes, and his sanity continues to go downhill. He also abandons his affection for Karai in "Requiem" and leaves her to die in a burning building; on top of that, he has seemingly abandoned his love for Tang Shen, which was [[LoveMakesYouEvil his former driving motivation for going after Splinter]], declaring that it's fitting that Karai should die in the same manner as her mother. Both Karai and Splinter even lampshade it, declaring that Shredder is now a monster both inside ''and'' out.

* The [[BigBad Big Bad]] from ''WesternAnimation/TheOwlHouse'', Emperor Belos, [[spoiler:originally started as an ordinary human named Philip Wittebane, but after developing an affliction during his stay on the Boiling Isles by trying to carve glyphs into his arms to try to control the magic, he begins to consume Palismen souls to keep himself alive, this inevitably leads to him mutating into a twelve foot tall, skeletal monster made of rotting, liquefied flesh, that is absolutely covered in glowing blue eyes. The Collector even suggests that ''this is now his true form''.]]
* ''WesternAnimation/PhineasAndFerb'': In "This is Your Backstory", Doofenshmirtz succeeds in getting enough of his backstories to make him more evil, and it turns him into a monster!

* In ''WebAnimation/BabushkaTheMovie'', the events of a famous round of ''VideoGame/AmongUs'' are depicted, and the more that the impostors LetsPlay/{{Valkyrae}} and Creator/{{Sykkuno}} kill, the more inhuman and demonic their appearance becomes. They look normal up until their second kills, at which point both briefly gain BlackEyesOfEvil with HellishPupils, although this only last lasts a second. (And Sykkuno briefly has [[RedEyesTakeWarning scary looking red eyes]] for a few seconds just before his second kill.) After Rae kills someone for the third time, her black eyes become permanent and at least from some angles it looks like she has fangs as well. See the video [[https://www.youtube.com/watch?v=3JmGQTMvO-U here]].

* In one issue of the [[ComicBook/TheLegendOfZelda Valiant Zelda comics]] Link steals the Triforce of Power from Ganon. As a result he [[PowerCorrupts starts turning evil]], and nearly completely transforms into a piglike monster similar to Ganon.

* As Sorceresses in ''VideoGame/FinalFantasyVIII'' grow older and continue to use their magic, their power begins to change their appearance into something less human and more monstrous. [[http://finalfantasy.wikia.com/wiki/Edea Edea]] was a fairly young sorceress so her appearance (while slightly altered) was still beautiful, whereas the older (and far crueler) sorceress [[http://finalfantasy.wikia.com/wiki/Adel Adel]] had morphed into a monstrous, muscular being. However, Sorceress [[http://finalfantasy.wikia.com/wiki/Ultimecia_%28Boss%29 Ultimecia's]] appearance is up for debate - her true form might be that of a winged, scantily clad woman, or her true form might actually be her barely human existence-sucking [[OneWingedAngel final]] [[http://finalfantasy.wikia.com/wiki/Ultimecia_(final_boss) form]]. Considering how the other sorceresses look, the latter is more likely.

* In ''[[VideoGame/{{Diablo}} Diablo II]]'', the protagonist from the first opus, after defeating the eponymous Demon Lord, has put his soulgem on his own body in an attempt to contain his evil. As the game progress, Diablo takes over his body, gradually making him more monstrous until he turns back into the [[OneWingedAngel hideous]] [[EldritchAbomination Demon form]] Diablo used to assume.

* ''Videogame/{{Undertale}}'''s Genocide Run downplays this in a way that's still terrifying, in that the child's sprite never changes, but their ''behavior'' does, and it seems their appearance changes in ways visible to other characters but not expressible in the artwork. Sans and Papyrus note that they don't emote (their sprite has a never-changing expression, but this is different), stare creepily, and shamble about covered in dust (i.e. monster remains- basically, it's fantastic BloodIsTheNewBlack). Other [=NPC=]'s become terrified of them when they get close to them, including Doggo, a character that's nearly blind, who remarks that he can't stop shivering when the child approaches. The kid also keeps walking through Papyrus's puzzles and the speeches of various characters, which both unsettles them and ticks them off. But the real kicker comes right after the introduction of Sans and Papyrus. Sans tells the kid that his brother would really love to see a human, and asks them to keep ''pretending to be one''. That's right, you've become so evil and twisted, ''you don't even register as human anymore!''

* As Sorceresses in ''VideoGame/FinalFantasyVIII'' grow older and continue to use their magic, their power begins to change their appearance into something less human and more monstrous. [[http://finalfantasy.wikia.com/wiki/Edea Edea]] was a fairly young sorceress so her appearance (while slightly altered) was still beautiful, whereas the older (and far crueler) sorceress [[http://finalfantasy.wikia.com/wiki/Adel Adel]] had morphed into a monstrous, muscular being. However, Sorceress [[http://finalfantasy.wikia.com/wiki/Ultimecia_%28Boss%29 Ultimecia's]] appearance is up for debate - her true form might be that of a [[EvilIsSexy sexy]], winged scantily-clad woman, or her true form might actually be her barely-human existence-sucking [[OneWingedAngel final]] [[http://finalfantasy.wikia.com/wiki/Ultimecia_(final_boss) form]]. Considering how the other sorceresses look, the latter is more likely.

* Creator/JRRTolkien was fond of this trope, probably because of his own spiritual beliefs. Orcs, for example, are corrupted versions of Elves turned evil by Morgoth. Many Men serving Sauron eventually turn to be like this, like the MouthOfSauron. Gollum (originally a Hobbit) is another example of a normally good creature turned monstrous from the influence of evil. Sauron himself was able to take on a handsome visage as "Annatar", but after committing more evil and helping to instigate the Fall of Númenor, he was unable to do so ever again.

** ZigZagged with the effects of Dark Warping in ''TabletopGame/PrincessTheHopeful''.
*** The majority of Darkened develop [[LovecraftianSuperpower Umbrae]] as they fall further into the Darkness, and when they hit zero Integrity they die and a bestial (and totally inhuman) Darkspawn is born from their corpse.
*** But on the other side of the coin you have Mnemosynes, those who were already so evil that they welcomed the Darkness in without a fight. As a result, they never developed Umbrae and retained their human bodies and minds. This means that they ''can'' pass for normal when they need to, not to mention being able to use tactics and make long-term plans.
** TabletopGame/VampireTheRequiem: The lower a vampire's [[KarmaMeter humanity,]] the less they are able to pass for human. While low-humanity vampires aren't necessarily hideous, they tend to [[UncannyValley seem weird and unnatural to humans,]] and often get pale and corpse-like. Having low humanity also changes a vampire's metaphysical biology to be less human-like, such as requiring them to drink more blood to survive and making them stay in torpors longer.

* The [[BigBad Big Bad]] from ''WesternAnimation/TheOwlHouse'', Emperor Belos, originally started as an ordinary human named Philip Wittebane, but after developing an affliction during his stay on the Boiling Isles by trying to carve glyphs into his arms to try to control the magic, he begins to consume Palismen souls to keep himself alive, this inevitably leads to him mutating into a twelve foot tall, skeletal monster made of rotting, liquefied flesh, that is absolutely covered in glowing blue eyes. The Collector even suggests that ''this is now his true form''.

* The [[BigBad Big Bad]] from ''WesternAnimation/TheOwlHouse'', Emperor Belos, originally started as an ordinary human named Philip Wittebane, but after developing an affliction during his stay on the Boiling Isles by trying to carve glyphs into his arms to try to control the magic, he begins to consume Palismen souls to keep himself alive, this inevitably leads to him mutating into a twelve foot tall, skeletal monster made of rotting, liquefied flesh, absolutely covered in glowing blue eyes. The Collector even suggests that ''this is now his true form''.

* Chucky from the ''Film/ChildsPlay'' movies. The more time he spends in the Good Guy doll, the more evil the doll looks (as well as slowly mutating from plastic to actual flesh and blood).

* Ben Willis, the Fisherman from ''Film/IKnowWhatYouDidLastSummer'', was originally a revenge-driven killer who used a hook as his WeaponOfChoice. By the time of ''Film/IllAlwaysKnowWhatYouDidLastSummer'' he's apparently become an undead ghost/living memory still driven to kill.

* ''Videogame/{{Undertale}}'''s [[KillEmAll Genocide Run]] downplays this in a way that's still terrifying, in that the child's sprite never changes, but their ''behavior'' does, and it seems their appearance changes in ways visible to other characters but not expressible in the artwork. Sans and Papyrus note that they don't emote (their sprite has a never-changing expression, but this is different), stare creepily, and shamble about covered in dust (i.e. monster remains- basically, it's fantastic BloodIsTheNewBlack). Other [=NPC=]'s become terrified of them when they get close to them, including Doggo, a character that's nearly blind, who remarks that he can't stop shivering when the child approaches. The kid also keeps walking through Papyrus's puzzles and the speeches of various characters, which both unsettles them and ticks them off. But the real kicker comes right after the introduction of Sans and Papyrus. Sans tells the kid that his brother would really love to see a human, and asks them to keep ''pretending to be one''. That's right, you've become so evil and twisted, ''you don't even register as human anymore!''

** In his first appearance, the {{sociopath}}ic [[CorruptCorporateExecutive industrialist]] [[BigBad Derek Powers]] is revealed to have produced a deadly biochemical weapon to sell overseas. He ends up [[HoistByHisOwnPetard getting exposed to some of the poison gas himself]]. After receiving emergency radiation therapy, he turns into Blight, a [[ILoveNuclearPower radioactive]] supervillain who looks like a glowing green skeleton. Now his appearance really matches his inner self.

* In ''VideoGame/LiveALive'', this is the fate of [[spoiler:the knight Oersted]]. Originally one of the most straight up heroic player characters in the game, he [[FallenHero falls]] after he is betrayed and abandoned by everyone he knows. After accepting the mantle of "Demon King", he seems to prefer his new monstrous form to his original appearance. [[spoiler:He reverts to his original human appearance right before he [[DeathEqualsRedemption dies while warning the other heroes not to repeat his mistakes.]]]]

* ''Literature/BazilBroketail'': Heruta's magical path to power has heavily altered his body. His eyes are fiery yellow and his entire body is covered in a layer of green horn-like tissue.

* ''Webcomic/ElGoonishShive'': Aberrations, the local version of vampires. You can't become one accidentally, you have to deliberately choose to become one, and becoming one means that you lose all human empathy and must prey on humans to extend your lifespan.