History NightmareFuel / Halo

* The screams of people falling from a destroyed Space Elevator. There's some very appropriately squishy sound effects to go along with the impact. [[NotTheFallThatKillsYou To think the ones killed by plasma fire were the]] ''[[NotTheFallThatKillsYou lucky ones]]''.
** Dimah was last seen on the Space Elevator. One of the falling bodies is wearing an all-white uniform.
** And the implication that they've been [[IFellForHours falling all that time]] since the debris from the collapsing elevator first fell on their heads.

** In that same note, Cortana's [[Literature/TheLordOfTheRings Gollum]] -esque "arguments" with her rampant mind in the episode's teaser:
--->'''Cortana''' ''(shrill, demonic voice)'': ''I hate you!''\\
''(as glowing sphere flashes bright red and distorts, unusually high-pitched voice, shocked)'': ''Cortana!''\\
''(shrill, demonic voice)'': '''''STOP IT!'''''\\
''(normal Cortana voice)'' I've made up my mind. ''(young girl's voice)'' If I'm going to die aboard this ship, ''then Chief will suffer the same fate as me!''\\
''(Elderly woman's voice)'': Cortana, ''control yourself!''\\
''(young woman's voice)'': ''I've'' sacrificed ''everything'' for '''''him!'''''

* he Ur-Didact's fate. He was trapped in that Cryptum of his for 100,000 years, and because the Domain was destroyed (something which ruined the Librarian's plan when she put him in stasis), [[GoMadFromTheIsolation he was left all alone, with only his madness for company]]. No wonder he's ruthless and genocidal by the time John frees him.

* The Special Applications Rifle, Caliber 14.5mm, SRS 99... aka, the Sniper Rifle System 99. While there are real life sniper rifles that do use large calibers, and sniper rifles that also use this caliber in particular, having a sniper rifle that powerful in ''any'' game would be OverKill and game over for anything that gets in its way, not to mention send most humans flying backwards. This is technically a nightmare ''for both, the Covenant and the Humans''.

[[folder:Halo: Combat Evolved]]
* Everything Flood-related, especially the first encounter with them in the level 343 Guilty Spark, which is loaded with creepy. See BleakLevel on the main page.
** The downed Pelican ("We're under attack by an unknown enemy! It isn't Covenant!"). The abandoned artillery pieces all facing away from you. The Grunts that used to flee at the mere sight of you run right into your killzone in a panicked retreat from something ''even scarier''. Strange shadows and noises seems to follow you through the trees. "Allies" appears on the HUD, only to disappear almost immediately without any trace. You follow the trail of carnage into a vast, underground complex, all painted in Covenant blood and deserted save for one man, a wounded Marine so insane with terror that he can't tell friend from foe. You wander deeper and deeper into the ancient ruin and finally find what's left of the rest of his unit. You download the feed from one unfortunate soldier's helmet camera, watch the entire squad get slaughtered... and then your radar goes wild. Even Master Chief looked briefly disturbed after watching the video feed.
** And the thing is that their introduction was a total surprise. There had been no signs in the instruction manual or anything in the game that indicated that it was going to turn into a horror movie. Yes, the Grunts were running away, but that could have been from anything. Everyone remembers when they first walked into the last room and suddenly a bunch of red dots appear on their radar, and then these jellyfish appear out of nowhere and start jumping at the screen.
* The Infection Forms seem to bounce off your shields, causing only minimal damage. A burst from the assault rifle can take down a lot of them at once. Surely the Flood are only a true threat for unarmored Marines, not a Mjolnir-equipped supersoldier like you. This is going to be easy. Then the Combat Forms show up...
** The Pod Infectors don't ''always'' infect their victims either. According to the helmet cam footage Chief finds, Pod Infectors can literally ''tear open'' their victims' chests if they don't feel like infecting them. In fact, it's possible to find the brutally murdered Elites seen in the helmet cam footage in CE. Where they are exactly is unknown, but successfully finding them can guarantee BringMyBrownPants for ''any'' [[https://youtu.be/iGVDpQMxQo4?t=546 player that so much as catches a glimpse of their mangled chests]]
** Sticking with the horribly mutilated Elites here, there's no actual explanation for why the pod infectors scrambled the Elites' chests. It's possible that the Elites were attempting to forcefully remove them from their chests and ended up ''removing a little more than the infection forms''. To make shit worse for you and your buddies, there are Elites that are disemboweled as well making it pretty obvious they were caught by surprise by combat forms that were able to rip their stomachs open before they could react, and you can actually ''see'' their innards and entrails still resting inside their stomachs. It's even more graphic if you're playing with the remastered graphics.
** It appears that only the Elites were brutally murdered (unless you want to count the poor Jackal with Grunt Blood ''splattered all over the fucking walls'').
** Even taking away from the initial horror of the sudden appearance of space zombies, you've seen enough movies and played enough games to know that zombies are only dangerous up close. After all, they're shambling, mindless corpses, right? That tune very quickly changed upon your first encounter with these particular zombies [[ItCanThink carrying guns.]]
* Bungie recently had an article that talked about the creative origin of the Flood. Upon being shown a single still picture of just one Flood form, the ESRB demanded the game be given an M-Rating. And that's without the lovely things mentioned above.
* The Flood music themes. Features Ominous EtherealChoir, PsychoStrings, and {{Scare Chord}}s. Special mentions go to "Suite Autumn", "Shadows", the ambient section of the "Truth and Reconciliation Suite", and "Library Suite". Above them all stands the Flood's main theme, and likely the scariest song in the entire franchise, [[https://www.youtube.com/watch?v=NpOVKbM7vlA "Devils...Monsters...".]]
** You thought the original Flood themes were scary? The ''Anniversary'' remixes turn the nightmare dial up to eleven: [[https://www.youtube.com/watch?v=njqFybTtD8I "Between Beams (Shadows)"]], [[https://www.youtube.com/watch?v=d_PXQFuNbNM "In the Substance of It" (not on the original OST)]], "Bad Dream (Trace Amounts)", [[https://www.youtube.com/watch?v=VcXJbton40w "Dewey Decimate (Library Suite)"]], "Demons and Heretics (Devils, Monsters)", [[https://www.youtube.com/watch?v=Dtl5IvMZ6NM "Unfortunate Discovery (What Once was Lost)"]] (now sounds like a Music/SunnO [[DroneOfDread drone doom]] piece) , "Xenoarcheology (Alien Corridors)" and [[https://www.youtube.com/watch?v=wM2Qd-Ij6VI "Fragments"]].
* Pvt. Jenkins, who got overran by the Flood and remained conscious after transformation! In the second book, he made attempts to throw himself into harm's way, but as luck would have it, he ended up being the ''only'' Flood form they captured alive for study. Throughout the book, his mind and the Flood's mind are battling it out.
* Captain Keyes' fate, getting turned into an immobile mass of flesh, only to get the sweet release of death when Master Chief burns him.
** According to the second book, he was slowly losing all his memories as the parasite took over. Towards the end, he was struggling to remember his own name! Furthermore, if you'd been around five minutes quicker, you'd be able to save him.
** Not only that, but in the game, at the start of that particular level, you start RIGHT OUTSIDE the room he's in, but of course you need to do the rest of the level first. Just take a peek through those grates to the right...
** In Halo: Anniversary, under him, there's a terminal containing his last moments from his point of view. He's repeating his serial number, and they're rifling though his memories...We see Miranda and Dr. Halsey, and those memories are being stolen, and he knows it, and his voice keeps switching between normal and Flood-toned. And then at the end, he swears, "You will not have me." And then the Flood speak again, and ''now it's the Gravemind'': '''"We already do."'''
** ''"Oh God. You don't want Earth. '''You want everything.'''"''
* Regarding non-Flood examples, pretty much all the aliens in the series look frightening in some way, whether they actually look scary like the Jackals or are just scary to fight against like the Hunters. It's made even worse in the first game by the fact that half the time you're in dim corridors and it's incredibly quiet, because of the suspense. Some more examples include:
** The Grunts. Yes, you heard right. It's hard to comprehend since we're seeing everything through the eyes of a seven-foot tall SuperSoldier, but they're still large aliens with disturbing-looking faces.
** The Elites (especially camouflaged Zealots) when they roar or when they're right next to you and you bump into them.
** The Hunters have no actual limbs. They're comprised of a bunch of worm-like things (1.4 meters) called Lekgolo that come together under their armor. In later games, they also make up the Scarabs.
*** The encounter with Hunters in The Silent Cartographer deserves a special mention. It starts with being dropped on to the beach by a Pelican, surrounded by allies, as you storm through countless easy Covenant enemies and enjoy the pretty scenery around you. You even get a Warthog halfway through, making the level even easier than it already is. But wait, the trees up ahead look too dense to drive through, so you begrudgingly leave your allies behind and head forward, figuring that if it was easy so far, what's the worse that could be up ahead? Suddenly, you come upon a clearing, and in it are two, huge, lumbering, armor-plated aliens making loud groaning and roaring sounds in the distance. Though intimidated slightly, you step forward, figuring that they probably can't be as tough as they look, only to have them shoot a series of explosive green blasts at you. You try to close the distance a bit and hope that melee will be a bit more effective, only to fly several feet forward after realizing that one of them has hit you from behind. The next one then charges at you like a roaring, alien freight train, and swings its massive arm at you, killing you in an instant.
*** In Truth and Reconciliation, two of them drop down from the gravlift while ominous music plays. At night. It's arguably worse. To make it even worse, the encounter on Truth and Reconciliation makes them seem unstoppable if it's your first time playing through a Halo game. Anyone who played Halo: CE as their first Halo game knows the sheer terror that pair brought upon you, cutting through all of your troops like they were nothing, deflecting sniper rifle bullets straight off of them, and grenades only making them flinch. However, the horror is slightly deflated when you eventually discover that a single pistol shot to their weak spot (their back) takes them out.
* Think of Master Chief [[MookHorrorShow from the Covenant's perspective.]] He's just one soldier, but he is perfectly capable of picking off entire squads one by one until every last fighter is dead and then move on to repeat the process ad infinitum. There's a reason he's called "Demon" by them in the sequels.
* ''Type-33 Guided Munitions Launcher'', more infamously known as the '''Needler''', is basically a terror weapon incarnate. Homing crystalline spikes that not only embed themselves in your flesh but also explode, breaking bones, displacing organs and tissue, further dispersing tiny flechettes of crystal in and near the wound and commonly to nearby people. If hit by multiple shards, you are as good as dead, but just one is incredibly dangerous.
* The entire purpose of the Halo array and the way it's slowly unveiled to you. At first, Halo is just presented as a mysterious megastructure. There's hints that it was built by the Forerunners, but its true purpose is unknown. Then you encounter the Flood. Along comes 343 Guilty Spark, who explains that Halo is a weapon designed to destroy The Flood.]] All well and good, right? Then, just as you're about to activate Halo, Cortana explains its '''true''' function: Halo doesn't kill The Flood, ''it kills anything The Flood can infect.'' Each of the 7 Halo rings can emit a destructive pulse that wipes out just about all sentient life within a 25,000 light year radius. Because the Forerunners figured that the only way to stop The Flood was to starve them to death, and the only way to do that is to ''kill an entire Galaxy.'' And as Halo 2 points out, the entire Covenant religion is based upon ''deliberately activating the rings.''
** One of the terminals in Halo: CE Anniversary has a (soon to be rampant) 343 Guilty Spark lament about how alone he is on Halo, guarding a weapon that has no target...which he says he could tune to ''any'' target.
[[/folder]]

[[folder:Halo 4]]
* The [[https://www.youtube.com/watch?v=3zcO28JbHxI intro]] alone DEFINITELY qualifies, as it shows oh-so vividly just how utterly heartless the [[ScaryDogmaticAliens Covenant]] were during the hellish Human-Covenant war when slaughtering innocent civilians, '''especially''' when it shows an Elite skewering one said civilian from behind the chest with its dreaded [[LaserBlade Energy Sword]].
* Some of Cortana's rampant screaming.
-->'''Cortana:''' I will NOT. ALLOW YOU. To '''LEAVE THIS PLANET!'''
** This line may also give you chills.
-->'''Cortana:''' Do you know what that condescending bitch said to me after our first game of chess?!
*** To put it in perspective, she's talking about Halsey, her "mother." The words she said to her after the game were '"Quando il gioco è finito, il re e il pedone vanno nella stessa scatola. [[note]] Translated from Italian to English: When the game is over, the king and the pawn go in the same box.[[/note]]
** One of Cortana's lines in the level "Composer": "Why should we save them?" It's like something out of ''VideoGame/DeadSpace''.
** Which is then followed up with a chilling chuckle, and an order to insert her into the station's defense grid. The way she says it seems like she was about to turn the guns on the MARINES.
* Promethean Knights. Their helmets opens up to a glowing skull, which screams at you. Worse, they are made of the victims of the Composer. Definitely makes that skull more terrifying in hindsight...
* The Composer must be powered by Nightmare Fuel because it is positively ''oozing'' horror:
** Chief and Cortana are too late to stop the Didact from taking it, unable to keep him from firing it, and then get the horrifying image of the people around them on Ivanoff Station disintegrating in ashes. And not instantaneously. '''''we see the skin peel off their bones'''''. You're even "treated" to a close look at its effects on Doctor Sandra Tillson.
** Worse, they weren't killed by the process at all, [[AndIMustScream which means they had felt the tremendous pain as their skin was being peeled apart from their flesh and their bodies]] ''[[AndIMustScream disintegrating]]'' [[AndIMustScream and still presumably felt the pain as they were cataloged by the Composer to later be turned into Promethean Knights and the sort by Didact to replace their dwindling ranks as Chief tore through their numbers]].
** Even worse, essentially, the Composer fatally digitizes people. Cortana is a digital lifeform. She's in shock afterward because she could hear the digitally fragmented minds/souls of the people, screaming in pain and terror. No wonder she was [[HeroicBSOD blue-screening]] when the Chief came to.
---> '''Cortana''': I was monitoring the data feeds. I could ''hear'' them...what was ''left'' of them...
** The Chief and Cortana are unable to prevent the Didact from firing it twice. The second time, it's on Earth, and the affected area in New Phoenix is still quarantined six months later.
** The people of New Phoenix were commonly believed to have received a MercyKill when Chief destroyed the Composer, but Episode 5 of Spartan Ops reveals that their memories were somehow transported to Requiem and transformed into Promethans...Spartan Thorn could be fighting his friends and family out there.
** A throwaway line in ''Literature/HaloSilentium'' will leave you with [[FridgeHorror endless horror once you realize the implications.]] When taking the personalities of humans defeated at Charum Hakkor, the Ecumene Council gave the Warrior-Servants and Lifeworkers "Composers"...as in ''plural''. That's right, folks. The Forerunners built ''more than one Composer!'' Every horrific thing you just read about the Composer? ''It could all happen again''...
*** Confirmed to be true in ''ComicBook/HaloEscalation'' Issue 9: The Didact is alive and operating from the Composer's Forge, where the Composers were built. He has ''six'' fully operational Composers. Fortunately, he seems to no longer want to Compose humanity. Unfortunately, he has since decided ''[[OOCIsSeriousBusiness he would rather use a Halo on Earth]]''.
** :The Ur-Didact's fate in ''ComicBook/HaloEscalation'' issue 10. Part of Installation 03 along with the Ur-Didact is dropped onto the Composer's Forge, causing all five Composers at nearby to detonate with the Ur-Didact seemingly disintegrating and ending up composed. However, WordOfGod has stated that he has not been completely composed in the way that is usually known due to the destruction of the Composers and the Ur-Didact's resistance to the Composer mentioned in the terminals in ''VideoGame/Halo4''. What exactly happened to him [[NothingIsScarier has not yet been revealed]] and the last shot of him was his glowing remains. All that is known is that he is still alive and will likely return to the narrative at some point.
* Related to one of the spoilered cases above, being killed in the other games wasn't that much of an issue, as the only thing shown is the character flying and\or collapsing, with not much resulting blood. The incinerating powers of the Forerunner weapons instead add the unnerving sight of Master Chief disintegrating as he burns to scattering ash. Even in the multiplayer it might be too much, as ''WebAnimation/RedVsBlue'' noted ("Umm... Did, everyone else see that?" "You mean a man disintegrate right in front of us? Really wish I hadn't.").
* The cutscene for Spartan Ops Episode 2 has Dr. Glassman being sucked up by a Forerunner artifact, complete with Capt. Lasky futilely trying to save him. With how his body breaks into glowing orangle particles just before he gets pulled in, it looks disturbingly like he's being Composed.
** Episode 3 reveals Glassman's fate. On the plus side, he hasn't been composed. On the minus side, he's been captured by the Covenant, and apparently is offering to trade information for his life; with Jul 'Mdama suggesting he'll end up RewardedAsATraitorDeserves after helping them. Also, the Artifact is apparently accessing systems aboard the Infinity, gathering information and transmitting it to Requiem.
* Episode 5 shows that the Promethean Majestic Squad are fighting are not ancient humans, but the victims from the New Phoenix incident six months before. Thorne said he knew people there. He would have been "killing" his friends and family... ''again and again and again''.
** I'm pretty sure its just once per person. Its kind of hard to restore data after its contain has been blown apart by a half dozen 8-gauge shotgun shells. Still quite disturbing, though.
*** It's not only entirely possible for Knights to come back after their body is destroyed, it's the entire ''purpose'' of the Promethean Watchers. Which adds an entirely new urgency to killing Watchers in gameplay: not only do they bring enemies back, they're bringing back those same people who composed ''again and again and again...''
* Episode 6, Chapter 5 has Crimson sent in after another Spartan team, Switchback, needed help taking down a Harvester guarded by Covenant and Prometheans. When Crimson arrives, all that is found are Switchback's removed IFF tags, nothing else. No clues are given to what exactly happened to them. The fact that the IFF tags were removed seem to indicate that they were captured. For what purpose? Likely nothing good.
** Becomes NightmareRetardant when it's shown that they were just captured, and only the leader was killed.
* Episode 7 in general. The Infinity is attacked by Covenant and Prometheans.
* The Flood combat in the War Games. Especially on a dark map, like Shatter. [[NothingIsScarier You're just looking around, watching fo-]][[JumpScare WHAT THE HELL WAS THAT?!]]
** Doesn't help that the Flood can use Armor Abilities as well. Seeing a Flood rocket towards you using it's thruster pack is nerve racking. Especially if your CQC aim is bad.
*** Also, the Flood models themselves. Look at one close up, and you'll see what I mean.
*** Specifically, you're looking at the first-ever ''Spartan'' Combat-Forms. Thank god they're just based on speculation as far as canon is concerned.
* Imagine being Roland when Halsey activates the former's override. Chances are, he won't want to hear the phrase "undid iridium" ever again.
* Halsey's severed arm in the Spartan Ops epilogue.
[[/folder]]

* Related to one of the spoilered cases above, being killed in the other games wasn't that much of an issue, as the only thing shown is the character flying and\or collapsing, with not much resulting blood. The incinerating powers of the Forerunner weapons instead add the unnerving sight of Master Chief disintegrating as he burns to scattering ash. Even in the multiplayer it might be too much, as ''Machinima/RedVsBlue'' noted ("Umm... Did, everyone else see that?" "You mean a man disintegrate right in front of us? Really wish I hadn't.").

* The Special Applications Rifle, Caliber 14.5mm, SRS 99... aka, the Sniper Rifle System 99. While there are real life sniper rifles that do use large calibers, having a sniper rifle that powerful in ''any'' game would be OverKill and game over for anything that gets in its way.

** Parts of the "High Charity" level are a BlackoutBasement. That's because the [[{{Precursors}} Forerunner]] dreadnought in the middle of the city was the main source of power for the city, and since Truth is preparing it for launch, it's disconnecting from the power grid. Imagine being a Covenant civilian, knowing that the Flood are spreading, desperately trying to escape, [[FromBadToWorse and then]] the lights [[OhCrap go out]]. Add to that the DroneOfDread [[https://youtu.be/-cwS6s4E4Go ambient track]] that plays throughout this section...

* Near the end of the war, when the infestation was at its zenith, [[HyperspaceIsAScaryPlace faster-than-light travel became phenomenally dangerous]], as [[SufficientlyAdvancedAlien slip-space was being deliberately altered by the Flood to better serve their interests]]. The Flood essentially ''[[OhCrap infested hyperspace!]]''

[[folder:Halo 3]]
* The concluding scene after taking down the large Covenant AA gun literally encompasses a dread-inducing feeling as any dedicated Halo fan immediately could tell what's happening in the following scene. After the Portal activates, a lone Covenant CCS-Class Battlecruiser is shown appearing from slipspace, strangely letting off a suspicious brown-colored smoke from its midsection. The Arbiter thinks it's merely more regular Covenant troops to deal with, boy is he ever wrong...
-->'''Arbiter:''' What is it? [[TemptingFate More Brutes?]]
-->'''Master Chief:''' '''[[FromBadToWorse Worse...]]'''
* Contrasting the previous games, now the Marines (as well as Elites and Brutes) can be [[FaceFullOfAlienWingWong "Floodiefied"]] in realtime. Yes, they transform into Combat Forms before '''your very eyes''', crying out in horror as the parasite tunnels into their chest cavity and takes control. Not to mention that if you manage to shoot an infected soldier in a way that doesn't make it explode and walk up to its body, you can see one clinging to the spine...
** Brute Combat Forms are a delightful new breed of horror - Instead of being neatly situated in the chest, as seen with human and sangheili Combat Forms, the Flood [[https://www.halopedia.org/images/f/f2/BruteFloodCombatForm.png in this case]] rests inside the Brute's ''throat,'' grotesquely distending their jaws so it can peek out.
** "[[https://www.youtube.com/watch?v=d1zWeaVZpsM Hunted]]". Talk about NothingIsScarier.
** The Flood Pure Forms, made entirely out of Flood biomass. You try to kill one of the [[BigCreepyCrawlies spider-like]] Stalker Forms, but it only ends up almost-instantaneously mutating into another form which tries to relentlessly kill you from afar or at close range.
* Perhaps the creepiest parts in the game are when the Flood start ''[[VoiceOfTheLegion talking]]'' to you. Hearing the Gravemind cursing and taunting you as his minions swarm you from every direction is ''chilling.''
* From the level Floodgate, the insane Marine considering suicide adds to the horrific atmosphere, much like the psychotic Marine in the first game.
** [[http://halo.wikia.com/wiki/AWOL_Marine Same]] voice actor for [[http://halo.wikia.com/wiki/Suicidal_Marine both]]. That guy is ''disturbing'' in-character.
** One line that the suicidal Marine said gives a [[BodyHorror good description]] of an infected person: "I could see it crawling, SLIDING AROUND BENEATH THEIR SKIN!"
** The very circumstances of the mission and its aftermath are horrifying. The quarantine space-blockade around High Charity mentioned in the folder above? [[EvilOnlyHasToWinOnce A single infested ship]] managed to slip through it and reach Earth. The town of Voi is overrun in minutes, the glut of bodies from the just-concluded battle of "The Storm" being reanimated left and right. In the end, while the arrival of the Fleet of Retribution helps stem the tide, the only way to prevent a full-on ZombieApocalypse is to [[TheOnlyWayToBeSure completely obliterate Voi and its surroundings]]; Miranda suggests overloading the infested spaceship's reactor core, while the Elites opt for OrbitalBombardment.
--->'''Rtas 'Vadum:''' One single Flood spore can destroy a species. Were it not for the Arbiter's counsel, I would have glassed your entire ''planet!''
** Really think about that for a moment. The Elites had enough ships in orbit of Earth to validate that threat, if they chose to devote the necessary time to it. Humanity had absolutely no say in the matter, being too weak to oppose their own ally and depending on them for survival. The only, ''only'' reason that Earth's biosphere wasn't destroyed that day... was because the Arbiter vouched for us in a conversation. The survival of hundreds of thousands of years of civilization was decided based solely on that exchange; it is literally the case in the ''Halo'' universe that if not for the Arbiter convincing the Elites to spare most of the Earth, a significant chunk of the human race would have been exterminated on the will of a single renegade fleet commander who spoke about the matter as if he was deciding what to have for dinner. PunyEarthlings has never been shown more subtly or terrifyingly.
** There's only two UNSC officers at the war conference on the Shadow of Intent, one of them being a relatively junior officer. The [[WatsonianVersusDoylist Doylist]] explanation is that Bungie wanted to keep the cutscene relatively light and only putting necessary characters in. The Watsonian explanation is that [[InferredHolocaust this is all]] the UNSC has left.
* Cortana has been captured and tortured. She has something that the Gravemind wants, and he will take it by force. As an AI, Cortana can't be raped in the traditional sense, but the UnfortunateImplications are still very much there.
* And here's this fun little message from the Gravemind if you listen to the Flood theme backwards: "Side by side, we march as one. Humans and Elites will die. The Earth will fall if we strike together. So forth shall all life."
* Browsing the terminals in the game. Between the lack of noise in many areas you find them in, the odd "swooping" sounds as you interact with them, the random alarm prompts and the oddly incoherent messages based around the apocalypse of the Forerunners and talking about the death of millions in many cases, it all adds together into a NothingIsScarier form of creepiness.
** "I SEE YOU RECLAIMER." Even more creepier than you realize that the one who sent those words was endicant Bias, the Forerunner A.I. who betrayed his masters for the Flood, which caused the first activation of the Halos. The final (Legendary) Terminal is almost [[SugarWiki/HeartwarmingMoments heartwarming]], though.
* Much like the previous games, the soundtrack has a few choice moments:
** First, we have ''Dread Intrusion'' played during the level ''Floodgate''. It starts off in the typical, already-creepy Flood themes but soon adds [[SubliminalSeduction back-masked speech]] from the Gravemind. Play it in reverse, and you get [[https://www.youtube.com/watch?v=YspMcFfCmZA this]]. The middle segment is an almost-heroic sounding drum but reminiscent of "Ghosts of Reach" from the Halo 2 soundtrack, but when it gets to the pause, instead of returning with doubled-up awesome, you hear a strange wailing screech come in, and it returns to creepy ambiance music.
** In the level ''The Covenant'', when the Flood shows up, the song ''Black Tower'' is played. Again, a voice is heard. Play it backwards and be treated to [[https://www.youtube.com/watch?v=RH39l43pWGw this]]. This appears to be a reference to T.S. Elliot's poem ''The Hollow Men''.
* Possibly Gravemind's creepiest line in any game. After Truth dies and Gravemind betrays you, massive tentacles burst up from beneath the platform the Chief and the Arbiter are on. This is then followed by insane, diseased laughter, followed by this:
--> '''Gravemind''': Now the gate has been unlatched, headstones pushed aside... corpses shift and offer room... '''a fate you must abide.'''
** His final words to the now Flood-infected Prophet of Truth right before the Arbiter silences him for good is no less chilling:
-->'''Arbiter''': I will have my revenge. On a '''Prophet!''' '''Not a plague'''!
-->'''Truth''': My feet tread the path.....''I shall become a God''!
-->'''Gravemind''': [[FateWorseThanDeath You will be]] ''[[FateWorseThanDeath food]]''. ''[[AndIMustScream Nothing more]]''.
** Truth's infection is [[BodyHorror particularly gruesome]]. Instead of the horrifying but thankfully relatively quick infections by way of Infection Form, Truth is slowly being overtaken by inhaling Flood spores, still conscious and able to speak and (weakly) move. Flood matter grows from his skin like tumours, and one ''BURSTS and releases a Flood tentacle that caresses his face''! The Gravemind is ''taking its sweet time'' with Truth, just because [[ItAmusedMe it amuses him]].
* The level ''Cortana''. There's a ''reason'' that's the least-played level.
** For those who don't know, this level is the one where you essentially break into the Flood's house in order to rescue Cortana. The "house" was originally a spaceship, but almost every wall, floor, and ceiling is covered in "[[MeatMoss Flood matter]]," which turn out to be oozing, infected pustules that spew enemies when shot. It's kind of like the halls of an insect hive. The Flood will attack from all sides (including up) as you try to navigate this somewhat-nightmarish landscape. It doesn't help that the level is somewhat confusing; many players get turned around easily even after several playthroughs. As you fight through it, you get to listen to Cortana's tortured, disjointed rantings and Gravemind's apocalyptic proclamations. Nearly all of Cortana's transmissions are either outright skin-crawling in their delivery, if not outright terrifying, with some carrying threatening tones in her voice.
** What's worse is that as the level progresses, Cortana's transmissions become more and more frantic and confusing, eventually becoming incoherent and horrific screams of pain...before she suddenly starts speaking in a lifeless monotone. Not only that, at that point, her graphics turn from blue to green. Also, the Gravemind moments become more and more "insane evil genocide monster."
*** ''"We exist together now. Two corpses in one grave"''.
*** ''A collection of lies, that's all I am! Stolen thoughts and memories!''
*** ''"Gravemind: (intrigued) "And yet, perhaps a part of her...remains?" (maniacal laughter, fades into ''Cortana's'' maniacal laughter). Her laughter is really unsettling.
*** ''"It was THE COIN'S FAULT! I wanted to KEEP YOU SAFE! Make you STRONG!"'' Made a ''thousand'' times creepier if you've read ''The Fall of Reach'' and know the significance of that transmission.
*** "''[[CreepyMonotone This is UNSC AI Serial Number CTN 0452-9. I am a monument to all your sins.]]''"
*** Equal part TearJerker and NightmareFuel of the NothingIsScarier variety, the very last "Cortana moment" you have before rescuing her is just her lying motionless on the floor.
*** Investigate the crashed pelican early on in the level and you'll hear Cortana talking over the loudspeaker. While not a "real" Cortana moment, what she says is [[DoesThisRemindYouOfAnything incredibly disturbing]]: ''"I ran, tried to stay hidden, but there was no escape! He cornered me, wrapped me tight... and brought me close"''.
** The background noise heard throughout the level, especially considering that the noises being made aren't made by any Flood forms you encounter, leaving what horrors could be found on High Charity up to one's imagination.
** Equal part [[Awesome/{{Halo}} Awesome]] and terrifying, when you finally rescue Cortana, the Gravemind has a VillainousBreakdown where it just '''roars''' in anger that the Chief has managed to throw a wrench in its plan. That's right, you essentially overcame an EldritchAbomination and it's pissed off that it failed to stop you on its home turf.
* 343 Guilty Spark]having a complete mental breakdown in the last level and going through a rampancy. It's very scary to see such an affable, if slightly annoying, character completely turning 180 and becoming an extremely dangerous foe who has lost his mind. Before it, you don't expect him to be a harmful threat, but then he proves you wrong ''big time'' by killing Johnson and burning the Master Chief. When you fight him, nothing works. Grenades, pistol, machineguns, sniper rifles, plasma guns, anti-tank weapons - none of them work. The only thing you can do is make him snap even further, and pretty soon you start feeling your heart pumping from desperation alone. [[RedEyesTakeWarning The red eye works, too, for the fear factor]].
[[/folder]]

[[folder:Halo Reach]]
* You haven't seen a Hunter in action until you've seen a pair use those damn Assault Cannons (essentially ''semi-auto'' high-explosive rocket launchers with BottomlessMagazines) to wipe out more than 15 friendly Marines in [[CurbStompBattle less than 10 seconds]] during "Tip of the Spear" in ''VideoGame/HaloReach'' [[note]]If you take out the AA gun before killing the hunters, they're still around when a Pelican airdrops reinforcements.[[/note]]. You duck behind a rock, reload your assault rifle, and when you come back into action, ''every last Marine'' which just got dropped from that Pelican is gone in a horrible subversion of TheCavalry.
* This game introduces a new piece of wildlife called the Gúta that could give the Flood a run for its money. Think of a [[VideoGame/{{Fallout}} Deathclaw]] but with elongated features. They are actually capable of killing entire ''squads'' of Elites, which are still feared at this point. The kicker? You encounter these things at [[DarknessEqualsDeath night]].
* The entire Covenant invasion on Reach. You're just sitting in your house watching TV or scrolling through a TV Tropes page when suddenly, you start hearing random explosions outside your house. You go to open your door and you see a '''Wraith''' launching plasma mortars at you! Anyone who has played Halo: Combat Evolved doesn't need to play Halo Reach to know what the Covenant are really capable of, but you never actually know the full extent of the invasion until you play Halo Reach, which shows just how cruel and genocidal the Covenant really are. There are also very few comical moments in the campaign, so you're practically playing one of the most depressing halo games of the entire franchise.
** The Lone Wolf campaign mission makes the invasion even more terrifying seeing as the player's character gets attacked by nearly every covenant within the vicinity. Not only that, but Noble Six never really lives to see the outcome of his selflessness.
* Want to see some small examples of how the [[AliensAreBastards Covenant]] conduct their infamous [[SaltTheEarth "glassing"]] business? Look no further than the "New Alexandria" level where you both experience it both audibly '''and''' visually in the far distance, [[https://www.youtube.com/watch?v=-gP8quhAj-U still within the city limits.]]
[[/folder]]

* Promethean Knights. Their helmets opens up to a glowing skull, which screams at you. Worse, they are made of the victims of the Composer. [[FridgeHorror Definitely makes that skull more terrifying in hindsight...]]

[[folder:Halo 5: Guardians]]
* The Legendary ending. Rogue!Cortana has ''a [[TheEndOfTheWorldAsWeKnowIt Halo]]''.
* It's hard to say which is worse: Cortana is still rampant, or she's ''not'' rampant and just [[WithGreatPowerComesGreatInsanity mad with power]]. Either way, when she shows her true nature to Fireteam Osiris, her ranting and sneering is just ''chilling''. Even worse is that she's utterly convinced she's in the right, that the Spartan-IV's and their kind deserve to ''die'' and that Chief will agree with her when she wakes him from stasis in 10,000 years.
** An [[WildMassGuessing alternative theory]] posits that not only may she be rampant, but that she is also infected with the logic plague or the AI equivalent of a flood infection from her time with the Gravemind in Halo 2 and 3.
* The ''Argent Moon'', the derelict ship of the eponymous second mission that Blue Team is sent to recover from Covenant forces. At first, you could be forgiven for thinking that the Covenant found it and killed everyone aboard. But it turns out the ''Moon'' was already a GhostShip long before Kig-Yar scouts stumbled upon it. ONI scientists had been working on an airborne bioweapon, and it somehow got loose. The result, as hinted by numerous dessicated corpses with an odd residue beneath them, was everyone aboard the entire vessel dying horrifically. According to a record by the shipboard AI, those who were at ground zero for the containment breach (who died instantly as their soft tissues ''liquefied'' as a result) were "the lucky ones."
* Hearing the Jackals [[AliensSpeakingEnglish speak English]] for the first time in the franchise is a little jarring.
--> FAAAALSE ARBITER! KILL! KILL!
* There's an EasterEgg on the multiplayer map "Rig". While the trigger for it is simple [[labelnote:*]] After GroundPound-ing a platform in the BottomlessPit in the middle of the map, you shoot two cores coming out of their silos, on the edge of the map.[[/labelnote]], the result isn't. You hear [[HellIsThatNoise a piercing screech]] as a rig on the horizon is suddenly lifted from below by ''[[AttackOfThe50FootWhatever a titanic]] SandWorm that makes Literature/{{Dune}}'s sandworms look like maggots.'' One can only hope that no one was on that rig.[[labelnote:Then again...]] This is just a simulation. Someone in charge of the simulation’s programming was probably messing around. Therefore, it isn’t likely that the sandworm even exists outside of the War Games simulation. [[/labelnote]]
[[/folder]]

* The concluding scene after taking down the large Covenant AA gun literally encompasses a dread-inducing feeling as any [[GenreSavvy dedicated Halo fan]] immediately could tell what's happening in the following scene. After the Portal activates, a lone Covenant CCS-Class Battlecruiser is shown appearing from slipspace, strangely letting off a suspicious brown-colored smoke from its midsection. The Arbiter thinks it's merely more regular Covenant troops to deal with, boy is he ever wrong...

** Sticking with the horribly mutilated Elites here, there's no actual explanation for why the pod infectors scrambled the Elites' chests. It's possible that the Elites were attempting to forcefully remove them from their chests and ended up removing a little more than ''the infection forms''. To make shit worse for you and your buddies, there are Elites that are disemboweled as well making it pretty obvious they were caught by surprise by combat forms that were able to rip their stomachs open before they could react, and you can actually ''see'' their innards and entrails still resting inside their stomachs. It's even more graphic if you're playing with the remastered graphics.

** It appears that only the Elites were brutally murdered (unless you want to count the poor Jackal with Grunt Blood ''splattered all over the fucking walls''.

** You thought the original Flood themes were scary? The ''Anniversary'' remixes turn the nightmare dial UpToEleven: [[https://www.youtube.com/watch?v=njqFybTtD8I "Between Beams (Shadows)"]], [[https://www.youtube.com/watch?v=d_PXQFuNbNM "In the Substance of It" (not on the original OST)]], "Bad Dream (Trace Amounts)", [[https://www.youtube.com/watch?v=VcXJbton40w "Dewey Decimate (Library Suite)"]], "Demons and Heretics (Devils, Monsters)", [[https://www.youtube.com/watch?v=Dtl5IvMZ6NM "Unfortunate Discovery (What Once was Lost)"]] (now sounds like a Music/SunnO [[DroneOfDread drone doom]] piece) , "Xenoarcheology (Alien Corridors)" and [[https://www.youtube.com/watch?v=wM2Qd-Ij6VI "Fragments"]].

*** "Release" takes it UpToEleven with a ''[[ThatsNoMoon massive]]'' flood base, and enormous tentacles to go with it. And it can't be destroyed or damaged in any way, because it's all part of the map.

* ''Broken Circle'' gives us a [[SarcasmMode delightful]] example in the Gravitational Refinement Device. ArtificialGravity, selectively taken UpToEleven as a means of torture. The device can [[SquashedFlat flatten the flesh and bone in a limb]]. The blood is either forced out [[HighPressureBlood away from the victim]] or can be moved up the body, [[LudicrousGibs into untargeted areas.]]

* The level ''Cortana''. There's a ''reason'' that's the least-played level!

* The BossBattle against Jega 'Rdomnai. It starts with the player hearing the voices of the Pilot's wife and child coming from a room in the third training course, and when the Master Chief picks it up, Jega starts speaking in time with them as they're bidding the Pilot goodbye, scraping his crimson-red energy blades across the ceiling and floor to add to the deathly-vibe in the room, all the while telling him he won't be leaving alive. He then decloaks, ignites some ''very'' scary-looking energy blades, and seals you in the room with him, remaining cloaked while creepily taunting you throughout the fight. Mercifully he's actually one of the easier bosses in the game.

* The BossBattle against Jega 'Rdomnai. It starts with the player hearing the voices of the Pilot's wife and child coming from a room in the third training course, and when the Master Chief picks it up, Jega starts speaking in time with them as they're bidding the Pilot goodbye, telling him he won't be leaving alive. He then decloaks, ignites some ''very'' scary-looking energy blades, and seals you in the room with him, remaining cloaked while creepily taunting you throughout the fight. Mercifully he's actually one of the easier bosses in the game.

* In a later-game mission, you begin to hear whispers from Cortana. Some are callbacks to things she previously said in the series, which can be tearjerking or nostalgia-inducing. Others? Others are cryptic statements spoken in rhyming verse of trochaic heptameter--the same speech pattern as The Gravemind.

* The Infection Forms seem to bounce off your shields, causing only minimal damage. A burst from the assault rifle can take down a lot of them at once. Surely the Flood are only a true threat for unarmored Marines, not a Mjolnir-equipped supersoldier like you. This is going to be easy. Then the Combat Forms show up...

* Perhaps the creepiest parts in the game are when the Flood start ''talking'' to you. Hearing the Gravemind cursing and taunting you as his minions swarm you from every direction is ''chilling.''

---> '''Cortana''': "I was monitoring the data feeds. I could ''hear'' them...what was ''left'' of them...]

--> '''Cortana''' ''(shrill, demonic voice)'': ''I hate you!''
--> ''(as glowing sphere flashes bright red and distorts, unusually high-pitched voice, shocked)'': ''Cortana!''
-->''(shrill, demonic voice)'': '''''STOP IT!'''''
--> ''(normal Cortana voice)'' I've made up my mind. ''(young girl's voice)'' If I'm going to die aboard this ship, ''then Chief will suffer the same fate as me!''
--> ''(Elderly woman's voice)'': Cortana, ''control yourself!''
--> ''(young woman's voice)'': ''I've'' sacrificed ''everything'' for '''''him!'''''

* There's an EasterEgg on the multiplayer map "Rig". While the trigger for it is simple [[labelnote:*]] After GroundPound-ing a platform in the BottomlessPit in the middle of the map, you shoot two cores coming out of their silos, on the edge of the map.[[/labelnote]], the result isn't. [You hear [[HellIsThatNoise a piercing screech]] as a rig on the horizon is suddenly lifted from below by ''[[AttackOfThe50FootWhatever a titanic]] SandWorm that makes Literature/{{Dune}}'s sandworms look like maggots.'' One can only hope that no one was on that rig.[[labelnote:Then again...]] This is just a simulation. Someone in charge of the simulation’s programming was probably messing around. Therefore, it isn’t likely that the sandworm even exists outside of the War Games simulation. [[/labelnote]]

-->''"We exist together now. Two corpses in one grave..."''

** Even taking away from the initial horror of the sudden appearance of space zombies, you've seen enough movies and played enough games to know that zombies are only dangerous up close. After all, they're shambling, mindless corpses, right? That tune very quickly changed upon your first encounter with these particular zombies carrying ''guns''.

* The concluding scene after taking down the large Covenant AA gun literally encompasses a dread-inducing feeling as any [[GenreSavvy dedicated Halo fan]] immediately could tell what's happening in the following scene. After [the Portal activates, a lone Covenant CCS-Class Battlecruiser is shown appearing from slipspace, strangely letting off a suspicious brown-colored smoke from its midsection. The Arbiter thinks it's merely more regular Covenant troops to deal with, boy is he ever wrong...