For a game about space ninjas, there sure are a large amount of scares to be had in here. And when we mean scares, ''boy do we mean scares...''

!The Infestation
* The Infested are made up of Grineer and Corpus alike who were unlucky enough to get infected. The [[ Infested Runners]] have a new arm growing from their chest and fused to their face and helmets like it was grasping at their skulls, the former Corpus now mutated into eyeless things with no purpose but to get close to an enemy, at which point they spasm and then ''explode'' in a spray of gore and nano spores. Others have been reduced to just a legless torso, pulling itself along with its flailing arms. The [[ Infested Chargers]], once Grineer marines, have been twisted into quadrupeds in the grossest way possible, their chests pointing up in the air with their limbs bent backward and joints inverted, a new "head" forming over their heart while their old skull hangs below their body. As for the [[ Ancients]], whatever they were before, they have no resemblance to it at all now. ''Pray'' that nothing of the original mind remains.
* Then there is Lephantis, a bio-engineered Infested monstrosity that was created for the Old War and survived by hiding in a derelict [[{{Precursors}} Orokin]] ship. It consumed and absorbed everything and everyone that discovered it, and so when you reach its chamber, it attacks you with giant, twisted versions of all three enemy factions. The Corpus head is especially horrifying, as the infested Crewman's helmet has fused with his skull and become a mouth that opens to attack you (compare [[ a normal Crewman]] to the [[ mutated version]]), and the Grineer head has a huge scythe which is basically an instant kill. [[spoiler: When you defeat the heads, the floor beneath you breaks, and you fall down to see Lephantis's main body, a building-sized monster with all three of the heads growing out of it. [[OhCrap Only then does the boss subtitle appear.]] ]] Doesn't help that all the while, Lephantis is [[ItCanThink sending you messages]] like ''"We are countless. Consume us. Be reborn."'' and ''"We embrace you. Why do you defile us?"''.
* A lot of the horror around the Infestation gets worse when you're familiar with the lore and realize that Warframes are likely based on the same technology as Infested. This is supported by the Excalibur Proto-Armor Skin for Excalibur which has the description, ''"Discovering the precise nature of this recently uncovered armored prototype has proved elusive. Initial attempts at dating point to ancient origins, perhaps even predating Orokin Empire."''. This is a direct reference to DE's previous game VideoGame/DarkSector, which had a very familiar threat called the "Technocyte Virus" that would take over hosts and warp their bodies, almost exactly as Infested do. In the darkSector universe it is nicknamed "The Great Plague" and an infested weapon in Warframe called the Mire also references a "Great Plague", hinting that these are one and the same, and Warframe technology was based off of the technocyte virus, and further supported by both dialogue in The War Within [[spoiler:calling the Warframe your Operator's "Infested Puppet"]] and the assertions of Cephalon Jordas in the J-3 Golem mission:
-->'''Jordas:''' ''"Tenno, it senses you are of like flesh, it is confused. Why do you defile us?"''\\
'''Jordas:''' ''"I see it now, you are the same. They fear themselves."''
* One only has to look at their behavior during an Infested rescue mission to see [[ItCanThink how smart they are.]]
* At the first day of Warframe, planet Eris was described as the location of a far-flung Corpus outpost. Now, every single mission node there are controlled by Infested. The [[AllThereInTheManual Cephalon Fragments]] for the planet describe it as being devoid of all life except the Infestation, which is slowly digesting the mutated ruins of Grineer and Corpus ships.
* Occasionally you will find a lone Corpus Crewman stuck in the Infested MeatMoss, struggling feebly to try to get out. You can either kill them yourself or leave them to there to be turned or torn apart by the Infested...
* Infested ships are claustrophic, full of deadly hazards that get worse as you kill more hive nodes, near-insta-kill poison enemies can trap you at close range, and there are so many infested in your face that you ''will'' start drowning in them if you don't have a decent piercing or crowd-control ability. All that's missing is the [[Film/{{Aliens}} M41A Pulse Rifle]]. To top it all off [[ this music]] plays throughout. Sometimes an Infested Charger can burst out of a vent next to you, Franchise/DeadSpace style, [[ParanoiaFuel even if you're on an Exterminate and have killed all the enemies.]] What's even worse are the Parasitic Eximi that constantly drain your energy and the [[GoddamnedBats Mutalist Ospreys]] which spew toxin fumes that directly damage your health. If you aren't prepared, hive missions can suddenly become Survival Horror.
* Infested Juggernauts. When they spawn, the lights flicker, similar to assassins, but [[HellIsThatNoise they also let out a terrifying roar]] which buffs all Infested around you.
* On some maps, in missions on planets where there is no Infested invasion, you can find in some innocuous corner somewhere a small patch of technocyte MeatMoss hidden and growing. No planet is truly clean; the Infested have footholds everywhere and will always, always return. [[ForeverWar The Origin System will never be free of them.]]
* As of March 2016, players can find [[ParanoiaFuel Infested tumors inside their orbiter.]] What's actually behind the door where the tumors are growing is a little unsettling, too: only Nidus can open it, where a chair with a device full of needles awaits. If you choose to sit in it, Nidus becomes infected with an Infested cyst. ''[[ThePlague Which can then spread to any other Warframe, causing them to visibly shrivel for a bit before growing the cyst as well.]]'' The cyst then begins to grow for one week, [[{{Squick}} getting nastier and larger before sprouting hairs as some real human cysts do.]] Thankfully, it's harmless, and can be drained once the week is over to create the [[spoiler: Helminth Charger, the strongest companion in the game.]] The cysts initially [[spoiler: shifted player alignment towards the Moon]] for infected individuals. Given the choices related to it, players started running from the cysts as if they were an actual disease.
* There's more to the Infested room on the Orbiter than just the chair and cysts. [[spoiler:''Something'' named Helminth resides down there, and it apparently serves Nidus. It wants Nidus to consume with it (fitting, given his territorial abilities.) As disturbing as it is, there's no getting rid of it since Ordis says [[MundaneUtility it controls the biological functions of the Orbiter]], but even he's disgusted by its existence.]]
* The Infested Salvage mission (and one stage of The Jordas Verdict) involves activating vaporizers to clear out Infested biomass and neutralizing the otherwise corrosive atmosphere. If your Warframe isn't inside a vaporizer bubble, you armor starts to corrode, and if it reaches 0%, you start to lose health, the edges of your screen turn red, and the Infestation starts ''speaking to you''. Even worse, the voices aren't coming from a proxy such as Jordas; the Infested [[HiveMind Hive Mind]] is speaking to you directly.
* As of the Pacifism Defect event, we get to see in real time what it looks like when someone succumbs to the Infestation, courtesy of the Grineer defectors in the Infested ship. First, they collapse like anyone does when they're out of health. Then, if no Tenno revives them in time, they're consumed by an Infested spawn pod, which creates a Charger. This is treated unambiguously as being a form of death for the Grineer.
* Operation: Plague Star saw the Ostrons' home of Cetus, as well as the Unum, come under threat from the Infestation thanks to a gigantic Infested Boil crash-landing on the Plains of Eidolon, something Councilor Hek sees as an opportunity to finally be rid of the Ostrons. Asking Konzu about what might happen should the Infested overrun Cetus causes him to give a chilling anecdote about how his uncle, a civilian merchant who sold rare materials in a market near Eris, was consumed by the Infested when they showed up and overran said market. Now, that market is a festering mess and Konzu's uncle's voice broadcasts on a beacon to any ships that happen to come upon the market, that the place they've found is a place of death and that anyone who could hear them should turn back before it was too late. Had the Tenno not intervened and fought off the Infestation, this would have been Cetus' fate.
** A full Tenno party mixing in Infested Catalysts to kill the boil can result in up to 4 Hemocytes (basically a bunch of ''Lephantis') and spawn pods appearing which results in an ungodly amount of Infested trying to murder everything as the boil's immune system's reaction...

!The Grineer
* The Grineer are a near-limitless horde of decaying clones that - aside from a few individuals mentioned below - possess two major psychological traits: Fanatical loyalty and love for their evil queens, and an equally intense hatred of ''everything'' that isn't them. And these traits are inherent to the Grineer as a whole. Sympathetic Grineer such as Clem, the Steel Meridian members and the Kavor defectors are all considered by their empire to be mistakes that need purging their functional consciences are explicitly described as a ''defect'' in the cloning process. Grineer are designed at the genetic level to be psychopathic killing machines. They have no [[UsefulNotes/TheLawsAndCustomsOfWar rules and restrictions on warfare]], targeting civilians just as often as they do combatants. Anyone they don't murder is rounded up and forced into slavery.
* Unlike the vast majority of mass-produced armies in fiction, they aren't weak, fragile incompetents that [[ImperialStormtrooperMarksmanshipAcademy can't hit the broad side of a barn]]. Each soldier is a extensively-trained professional killer, the vast majority of which are heavily armored with strong alloy plating. Their bodies are heavily augmented at the genetic level for stength, endurance, and durability. They use extensive cybernetic implants to increase their already formidable capabilities and shore up any physical flaws, while also linking them to their - ''very effective'' - weapons in a way that lets them wield those weapons like an extension of their own body. Lore-wise this makes every Grineer soldier a crack shot with their guns, as well as highly adept at hitting you with melee weapons in ways that will do the most damage. And [[WeHaveReserves they have more reserves]] [[UpToEleven than you would ever believe possible]].
* Vor's ominous threats and taunts as [[spoiler:his Ascaris slowly takes more and more of you over]] in Update 14, culminating in this line that replaces the Lotus' standard "Mission complete" dialogue at the end of the Corpus Hijack mission.
-->'''Vor:''' You are '''MINE'''.
* Running high-level Void missions reveals that after you killed him, [[spoiler:[[CameBackStrong Captain Vor didn't stay dead]] and is now loyal to ''something'' that dwells within the void]]
* Grineer Manics. You're just going about a mission, happily killing things until you start hearing this insane laughter and then these things show up. They can be seen as mini-Stalkers, seeing as they can turn invisible and invulnerable, [[HealingFactor can regenerate their health,]] can [[NoSell Dispel]] your abilities, and can easily kill you if you're not cautious.
* The Grineer Blackout tactical alert. [[NothingIsScarier There are no enemies]] until you reprogram the navigation computer. Then 75 Grineer Manics appear out of nowhere...
* [[ Vay Hek addresses the Tenno directly.]] The fact that the video appeared exactly at the end of a developer livestream interrupting it mid-sentence without warning increased the effect.
* Before the Grustrag Three show up, the Lotus contacts you about 'impossible readings' she is picking up nearby, and her transmission is abruptly cut off. She gets out a few more garbled transmissions about how you are 'being hunted' and then suddenly begs the Tenno to abort the mission ''now'' before she is cut off totally. [[NothingIsScarier There's a few seconds of nothing]], then the Three spawn into the level. If you aren't equipped properly, they ''will'' beat the snot out of you, trap your Warframe under an orange cage-thing, and fix it with a RestrainingBolt that makes it almost impossible for you to effectively fight other Grineer. The ''genuine concern'' you can hear in her voice is what really hammers home what a threat the Grustrag Three present to the Tenno. While the Lotus obviously cares about you, she is nothing but utterly calm or mildly surprised at most, even on the most dangerous missions. Suddenly, she is [[OOCIsSeriousBusiness clearly frightened and confused]], frantically warning at the player to abort and ''run'' before getting cut off.
* The War Within, while grim, hides it's horror more subtly. [[spoiler: For example, the Queens know exactly who you are, and about Ordis. The Elder Queen also states the reason why her possession didn't work. She spends the quest slowly but surely corrupting you, culminating in you moving as she does.]]
--> '''Elder Queen:''' I see how you cast me out. Simple really. [[spoiler: There's no room for me in that head of yours.]]
* In the Pacifism Defect event, the Tenno are tasked with escorting Grineer defectors from Sargas Ruk's army (who aren't trying to join the Steel Meridian, but just want to live peacefully) out of ships that have been hit with the Infestation. When most Grineer speak, their voices are rough and almost monstrous, distorted by their cybernetics. Not so for these defectors. Despite not having their dialogue appear as text on the screen (which makes them feel more like regular Grineer [=NPCs=]), they sound like completely normal human beings. That makes it all the more nightmarish when they start dying to the toxic air in the ship. Their desperate screams are haunting.
-->'''Kavor Defector:''' ''TENNO, THIS IS KILLING US!''
* In the higher-level missions of the Pacifism Defect event, Sargas Ruk begins sending in [[BossInMookClothing Grineer Manics]] just in case the Infested don't kill enough of the defectors. It doesn't matter that the escaping Grineer simply want to live peacefully and will pose no threat to anyone once they're out: [[ResignationsNotAccepted their superiors still want them dead.]] Life as a Grineer subject seems bleaker by the minute.
* The Nox unit is one of the nastiest things in the Grineer army. Its codex entry describes it as being filled with toxins, and their suits have a noticeable cloud inside them, which vents out if their helmets are broken. Their face however, is simply unpleasant to look at. [[BodyHorror Its almost entirely swollen, and looks as if its covered in boils and scars.]]
* Ghouls. These are special Grineer units deployed as shock troops. What makes them special is that instead of being a fully grown Grineer clone, these guys are quickly gestated in diapause bags, creating near-mindless [[BodyHorror malformed beasts]] with an [[TheBerserker incredible bloodlust]].
** The Auger has practically no lips, carries [[ThisIsADrill two large drills]], and loves to dig underground, leaving you with almost no idea of where it is and when it'll pop up.
** The [[ActionBomb Expired]] is a Ghoul who suffered from malnutrition or poisoning while in their bag, leaving it with more deformities than other Ghouls. How much? Its head is more resembling of a skull, even lacking a nose. Its "umbilical cord" is also still attached to it, flailing about as it try to [[TakingYouWithMe blow you up along with them]].
** The Rictus has an oversized neck and carries a [[ChainsawGood large saw]], which it will happily use to carve up any non-Grineer it finds.
** The Devourer is arguably the worst out of the lot. It's an enormous Ghoul with a very large maw, allowing it to consume enemies who are unfortunate enough to get to close. It won't matter if you're not to close either, as the Ghoul will either grab you with its hooks, or charge you down with incredible speed. The Devourer is also implied to only have one eye in its head.
** You wanna know the scariest part about the Ghouls? The Grineer can bury them in the ground ''from orbit'', allowing them to develop while any nearby people remain unwary. They'll have no idea that their nightmares are lying right beneath their feet before it's too late.
** A miner, fisherman, or scout on the plains could be going about their daily business, oblivious to the monsters lying dormant in the ground. They take one step in the wrong direction, and BOOM, a savage beast leaps out of the ground and barrels toward the one who disturbed it. One can only imagine the terror going through the head of person caught in the sight of a Ghoul.
** And the one who created these monsters? Doctor Tengus, the same guy responsible for creating the Grustrag Three, unleashing the Infestation upon the Origin system, and [[spoiler: making Vay Hek the way he is now]]. This goes to show just how twisted Tengus is, and to what extents the Grineer will go to conquer the Origin system.

!The Corpus
* The Zanuka Project: various sliced-up Tenno and their warframes formed into a mechanical quadruped controlled by Corpus technology. [[spoiler:What the hell this does to the unfortunate Operators on the other side of the Warframes in question is unclear.]]
* Valkyr, the Warframe produced as a byproduct of the Zanuka Project. All subsequent Valkyr frames are based off of the template of the original. It's impossible to tell what frame Valkyr used to be, or if we've even seen it yet, but that's not even the scariest part. Given that Warframes draw their power from the [[EldritchLocation Void]] in a manner that is suggested to be intrinsic to their psychology and outlook on life, it suggests that whatever Alad V [[ColdBloodedTorture did to Valkyr]] caused her psychology to [[MindRape change so drastically]] it ''altered her Void imprint''; [[spoiler:and knowing what we do now, the implication seems to be that Valkyr's original Operator was ''linked to it'' during the entire procedure, which seriously starts to approach [[Anime/NeonGenesisEvangelion Asuka Soryu]] levels of [[BodyHorror character]] [[MindRape horror]].]]
* Valkyr's original (non-Prime) form is demonstrated by her Gersemi skin. With it on, she looks like a fairly normal Warframe. There's just one little detail: The Gersemi skin bears an uncanny resemblance to that of Zanuka. Now we know where Zanuka's outer layer came from.
* "The Profit" Trailer [[DownerBeginning begins]] with Alad V cutting up an Excalibur, then preparing to do the same to a Mag. It's unsettling enough that Alad maintains a friendly, affable veneer throughout the whole thing and it's unsettling enough that he treats the whole thing like an auction (with prospective buyers!), [[spoiler:but knowing that the Excalibur he cut up is still connected to his Operator - and knowing that that is true for ''every'' Warframe he cuts up for the Zanuka Project - adds a horror to the whole thing that puts it up there with what happened to Valkyr.]]
* Ever wonder why there are so few female Corpus mooks? Corpus crewmen are described as 'purpose-bred'.

!The Sentients
* Story-wise, what little information we have of the Sentients leans them towards this. These are something so threatening that the Orokin unleashed the Technocyte Plague and the Tenno in order to try and stop it. They pilot "worm-ships" which use heat-bursts to boil their enemies from the inside, are described as having "multi-faceted eyes", and are nearly endless in number.
* The Tenno were chosen to be used in the war because their powers were spawned from the Void-- a "hellspace where science and reason failed"-- and thus couldn't be subverted by the Sentients, who were getting stronger with every advance the Orokin fielded. Lotus reinforces this in Vor's Prize, pointing out that the presence of the melee weapon was an adaptation to the Sentients' ability to subvert technology.
* Ember Prime's codex entry implies that the Orokin were so desperate that they even [[spoiler: threw ''kids'']] into the Void. [[spoiler:It was more an accident, really, but the effect was the same.]]
* You have read all of the entries here, yes? The Sentients are '''returning'''. Unless you've seen the trailer for Tombs of the Sentient, you won't know when Teshin, the Conclave master, references them. All you'll know is he's trying to prepare you for the evils returning from beyond the outer terminus. Need we remind you again that the relic you interact with in ''The Second Dream'' quest is [[spoiler: the corpse of Lotus' father, Hunhow? Yes, that one gigantic pillar stuck underwater allllll the way up to the surface of Uranus is only a part of it!]]
* [[spoiler:After competing The Second Dream and going back to Lua, you can run into Sentient Oculysts that can then summon either Sentient Battalysts or Conculysts that can adapt to your attacks just like they did in the Old War. The screen flickers blue like as if an Assassin is spawned and a loud metallic screech sounds that signals the appearance of both the Oculysts and their Sentient fighter backup, and while you fight them the Background Music is replaced with a hollow-sounding wind.]]
* [[spoiler:The Shadow Stalker first appears as The Second Dream's main antagonist and takes the Stalker and turns him into a pawn of the Sentient Hunhow, replete with frightening armor attachments and Hunhow's sword, War. His appearance at the Climax of The Second Dream when he confronts the Operator within their Orbiter's Somatic Link, stabs their Warframe with War, and attempts to strangle the Operator is one of the most frightening sequences in the entire quest, and Hunhow's dialogue only ups the tension. After completing The Second Dream he will also replace the regular Stalker and while he's not as much of a threat since he doesn't have his bow, throwing knives, or SinisterScythe, he still has War and he also has the Sentients' ability to adapt to your attacks.]]
* The Sentients are capable of subverting all forms of Orokin technology, at least if it's not touched by the Void. This even includes [[spoiler:Cephalons from the Orokin Era, namely Cephalon Suda. And then, because these Cephalons are interconnected, they can spread their mind control to other Cephalons. And even better, by controlling only one Cephalon, they could have gained the power and resources of a enitre Syndicate, with only you, Ordis, and Simaris the wiser. And they nearly kill Ordis and the Operator as well.]]
* In ''Plains of Eidolon'' trailer: [[spoiler:a gigantic structure of Sentient origin lies dormant near a civilian colony. Then ''[[ThatsNoMoon it moved]]''.]]

!The Tenno
* The Tenno themselves. Almost completely silent killers, who can strike almost anywhere and at any time. Their nature is largely unrevealed as well. All we know is that those who made it back from the void [[CameBackWrong came back wrong]]. High ranking Tenno can and will single-handedly wipe out entire armies, from lowly grunts to the elite of the elite. The only enemy who regularly gives a well equipped Tenno pause is the Stalker.
* What happened to the original Limbo. Specifically, the way it's described to us.
-->'''Ordis:''' Oh, wait, Limbo, no that's a mistake, you don't want to go there. It's too big a jump. You can't rift walk... ohh. Oh no. Operator, I think I know [[TeleporterAccident why we're finding Limbo parts scattered throughout the system]].
* The Tenno are MookHorrorShow incarnate if you think about it. They're terrifying and unstoppable OneManArmies, each with their own personal style of slaughter. From Volt's ShockAndAwe, Ember PlayingWithFire, and Saryn being a PoisonousPerson they're all uniquely terrifying. They fly around in stealth ships and can show up anywhere. From the most isolated outposts to secure fortresses, at any time. And they are nigh-impossible to stop.
** With just a competent 4 man team, each Tenno can rack up 300 kills each, in less than 20 minutes against an army of trained killers. In half an hour, a Tenno can kill close to a thousand Grineer during a survival mission.
* Let's talk about Hydroid. His 3rd ability, Undertow, allows him to become a puddle of water and move around in it. While it sounds useless, this puddle is somehow as deep as the ocean itself despite being able to see the bottom of it, and anyone unfortunate enough to step into it will be plunged underneath. And unless someone/something is able to disrupt Hydroid channeling the spell, [[AndIMustScream Nothing can ever get you out before you drown]]. Hydroid's water form can look like ANY other gathering of water, and is completely silent, with little in the way of visual/audio cues, meaning you can step straight into your slow, painful death before you even begin to figure out what happened. Even if you see the puddle, Hydroid is [[NighInvulnerability completely invulnerable]] while in this form, and can summon tentacles to pull you into the puddle from a distance.
* You know how the Warframes have no face? Evidently, at least ''Rhino'' does, and [[ImAHumanitarian he's pretty fond of snacking on his victims]].
* The War Within gives us details that definitely fall into this category:
** [[spoiler: The Zariman Ten-Zero incident.]]
--> [[spoiler:'''Elder Queen:''' Paranoia gripped your father's mind. What was it he said - as he stared out into the [[EldritchLocation starless black]]?\\
'''Operator:''' Something's out there kiddo... watching us.\\
(Later in the quest)\\
'''Elder Queen:''' You remember then, how the howling stopped - [[GoMadFromTheRevelation they]] had broken through.\\
'''Operator:''' (Moon) They were nothing but animals... so I hunted them.]]
** [[spoiler:The trials your Operator has to go through to unlock all of their Void powers. You have to use your powers to navigate underground fields of ''bones'' patrolled by ravenous Orokin Maws, which are mechanical {{Sand Worm}}s. [[NonStandardGameOver Get caught by one of the Maws]], and you get treated to the sight of one grabbing your Operator in its prongs, [[EatenAlive then dragging them under the bones so that the Maw can eat.]]]]
** [[spoiler:After defeating the Grineer Queens and unlocking all of your Operator's Void powers, you meet Master Teshin on the same snowy peak where you fought your BattleInTheCenterOfTheMind against the Elder Queen, still in possession of the Kuva Scepter you stole from her. After conversing with Teshin about what to do with the Kuva within the scepter, you get a choice: Destroy the Kuva (Sun Alignment), let Teshin Control it (Neutral Alignment), or Consume it (Moon Alignment). Whichever choice you go with, your Operator is suddenly ''controlled'' by an entity called "The Man in the Wall", who is implied to be connected to the Void and the Tenno's powers. Their eyes turn deathly black and the background darkens while they deliver an utterly ''chilling'' line:]]
-->[[spoiler:'''Man in the Wall!Operator:''' (Sun) [[VoiceOfTheLegion You mad at me,]] [[WhamLine kiddo?]] [[VoiceOfTheLegion Did you forget?]] '''[[VoiceOfTheLegion You owe me.]]'''\\
'''Man in the Wall!Operator:''' (Neutral) [[VoiceOfTheLegion Don't forget,]] [[WhamLine kiddo]]: '''[[VoiceOfTheLegion You're nothing without me.]]'''\\
'''Man in the Wall!Operator:''' (Moon) [[VoiceOfTheLegion Hey,]] [[WhamLine kiddo]]. '''[[VoiceOfTheLegion What took you so long?]]''']]
* ''[[MadnessMantra Rap. Tap. Tap.]]'' Chains of Harrow is, to put it scientifically, creepy as fuck.
** It starts with a playback of a Steel Meridian transmission, during which the screen subtly turns blood red, then fades to black, and an electronic groan is heard before the screen returns to normal.
** After the end of the quest [[spoiler: your Operator will be happily sitting in the cockpit to greet you after freeing Rell. But then you realize that you can still control your Warframe...meaning that isn't you. If you walk up to it, you hear something you never would have wanted to hear a second time:]]
-->[[spoiler:'''The Man in the Wall:''' [[VoiceOfTheLegion Hey, kiddo.]]]]
** [[spoiler: After that happens, the being disappears as soon as you turn away from it. And after the first encounter, there's a chance that the Man in the Wall will randomly appear in your Orbiter after completing a mission, delivering its line and summarily vanishing. [[ParanoiaFuel There's no way to tell where or when it's going to appear.]]]]
** [[spoiler: If Palladino and Rell are to be believed, The Man in the Wall is an avatar of the Void itself. [[GeniusLoci The implications of this are chilling.]]]]
** [[spoiler: Everything you've been doing, gaining your strength to fight the Queens, releasing Rell... It's only making The Man in the Wall stronger. As the Tenno grow stronger, '''so does he'''.]]
** [[spoiler:Despite the Lotus's insistence that it's just a delusion, The Man in the Wall seems to be becoming more active.]]
** [[spoiler:Once you complete The Sacrifice, ''it talks with you about what happened.'']]
-->[[spoiler:'''The Man in the Wall:''' [[VoiceOfTheLegion Feelin' better,]] [[TermsOfEndangerment Kiddo?]]\\
'''Operator:''' [[ItsAllMyFault I killed him...]] ''[[ItsAllMyFault Isaah.]]''\\
'''The Man in the Wall:''' ''[[IShallTauntYou Did you now?]]'' Is that how you remember it?\\
'''Operator:''' Yes.\\
'''The Man in the Wall: Good.]]'''
* Nekros: The Death Themed Warframe and NightmareFuel Personified.

!The Orokin
* The [[AbusivePrecursors Orokin]]. Just the Orokin. Each new bit of lore focusing on them reveals a new, ''incredibly disturbing'' level of dehumanization, scientists with {{Morally Ambiguous Doctorate}}s, and incredibly unethical experimentation; which gets even worse when it's revealed that the Tenno are [[spoiler: {{Child Soldiers}} who haven't aged a day since they entered cryostasis centuries ago. The Orokin considered it acceptable to take casualties from a horrific {{Teleporter Accident}} and turn them into soldiers just to make use of the destructive powers the Void gave them; to the point where they killed their ParentalSubstitute to make them even more efficient. These silent masters of warfare, [[MookHorrorShow capable of slaughtering absolutely anything in their path]], are ''less than seventeen years old'' when they finally wake from stasis. And they've experienced all those battles as if they were there in person, thanks to their Warframe proxy units.]]
** In ''The Sacrifice'' it's revealed that the Tenno can use warframes because they have something the Orokin lack and don't understand: '''basic empathy''', as stated in a record created ''by'' an Orokin.
* The [[EldritchLocation Void]]. Pristine. Beautiful. [[LostTechnology Transcendent]]. Utterly empty except for "corrupted," versions of enemies you face in normal levels turned into mindless drones by dying in the Orokin Towers they invaded and being turned by these Towers' Neural Sentries. The music that plays here is simultaneously serene and unsettling. Look out a window and all you'll see is black dots in an endless white expanse. It begs two questions when you first set foot in them - who were the Orokin, and where did they go?
* In Specters of the Rail, we finally learn of Ordis' origins. [[spoiler:He was originally a soldier/mercenary named Ordan Karris, who fought for the Orokin for so long and so viciously that he became known as [[NamesToRunAwayFromReallyFast the Beast of Bones]]. When he was brought before them to honour his service, he used the opportunity to [[KillTheGod kill as many of them as he could]]. Unfortunately, they had planned for this, and his assassination attempt failed. As punishment for his treason, they subjected him to a process that converted his mind into a Cephalon. All parts of his mind that weren't needed were locked away, and any thought of rebellion was suppressed by what is implied to be a neural sentry. After the fall of the Orokin, the sentry broke down, leaving Ordis free to remember. He ended up locked in a loop of trying to recall his past, then wiping his memory in horror when he did. Of note is the weapon he uses to carry out his plan. Known as "Bone plugs", they are hooked fragments of bone that are embedded in the wielder's neck, wrapped around the superior vein. When used, the wielder pulls them out to use as daggers, so they only have a few seconds before they [[TakingYouWithMe succumb to blood loss]].]]
* [[spoiler:The nature of [[GrandTheftMe Orokin immortality]]. Orokin reaching a point where their bodies are on the verge of death go to Yuvan theaters where the young and exotic - often no more than ''children'' - are paraded and sold like slaves, to be used as those Orokin's new bodies in the "Continuity" ritual. How do they do this? By {{Mind Rap|e}}ing these kids until they're little more than an EmptyShell that the Orokin can freely insert their minds and souls into. And you learn this during The War Within, ''while you're fighting a BattleInTheCenterOfTheMind to stop one of the Grineer Queens from doing exactly that!'']]
* Mild one in ''Plains of Eidolon'' trailer, where the villagers going about their daily lives, dismantling what seems to be... flesh... from an abandoned Orokin structure... Just what did they use to build it is anybody's guess. Which also raises the question: Is it possible that ''other'' Orokin structures and machines are like this? Are the Orokin Towers made of this? Your sculptures? Your ships? Your weaponry?
* [[spoiler:Ballas, the creator of the Warframes and by far one of the most influential of the Orokin, ''is still alive''. We get to see a true Orokin in all of their glory and it is nothing short of terrifying. His skin is a pale blue, his eyes have pale golden irises, and his right arm is extremely [[BodyHorror elongated]]. If the Orokin considered this to be beauty, just imagine what an ugly orokin looks like.]]
* How warframes were ''originally'' made. [[spoiler: While now the Tenno have Helminth to harvest for the creation of their frames, the first frames were made by ''pumping people full of Infestation until they transformed into an armored, berserk combatant'']].

!Everything else
* [[AndIMustScream Let's just say that you don't want to fail a Rescue mission by tripping an alarm and failing to get the hostage out]]. The fact that it was audio only doesn't help. In a similar vein, the way capture targets howl as you capture them. Were it not for the ''Stolen Dreams'' quest, you could be forgiven for thinking you were subjecting them to torture or a FateWorseThanDeath.
* The Stalker, if you aren't expecting him. You're out, minding your own business, celebrating a boss' defeat, when suddenly, the lights flicker. Then:
--> '''Stalker:''' [Player], you cannot run from your past.
* During the ''Second Dream'' quest when the Stalker [[spoiler:put his War greatsword through your Warframe, he was [[DeathGlare looking at the Operator the entire time]]. Then there's the fact that the Warframe that was just described as a mindless machine, takes War, the current source of the Stalker's power, ''[[ItCanThink and breaks it]]''.]]
* The premise of The Second Dream. You spend quality time with your nice and cozy Warframe [[spoiler:then you get decked back out into your unfamiliar body, dazed and confused,]] while a dozen Sentients are out for your blood...
* Reaching the lowest reputation possible with New Loka makes them suddenly dial the creepy-factor up to eleven if you then visit their syndicate menu. Given their flavor text and some of the rather unnerving statements New Loka's leader says even when she likes you might point to a [[ANaziByAnyOtherName much darker intention]]. [[spoiler:Some players even wonder if New Loka [[YouHaveOutlivedYourUsefulness might target]] the 'impure' Zariman children once the war is over if they ever found out what the Tenno really are]].
-->'''Amaryn:''' You're just like the rest. Tainted and ruined beyond salvation.
* On the relays, some of the Red Veil are preparing to vivisect a captured Grineer. Also, they have several infested in a cage, for unknown purpose.
** Said infested, which is used by the Red Veil as a hit squad, is a Charger, a horribly mangled Grineer corpse. Now, [[FridgeHorror what could they want with a Grineer captive?]]
* Desert Skates, at least once you see their underside, are pure BodyHorror. Seriously, [[ that is not the face of mercy.]] It's easy to think that the average Desert Skate WasOnceAMan, even though skates are real animals related to rays and sharks and their undersides are [[ quite normal looking...]] compared to other rays and skates.
* The cryptic message you find in the Orokin Derelict at the end of the Stolen Dreams questline. It comes from the Popol Vuh, a '''real-life''' Mayan text that details their creation myth.
-->All-All is silent- Hushed-hushed and empty is-is-is the womb of the sky.
-->'''All is silent and calm. Hushed and empty is the womb of the sky.'''[[note]]Those lines were used to describe the 'primordial world', what existed before the world itself was created.[[/note]]
* The Apostasy Prologue. [[spoiler:Ballas has returned. Margulis has abandoned us.]] [[spoiler:The Lotus is gone.]]
** [[spoiler: The hidden quest leads the player through the Moon, following a trail of light and sound recounting the final moments between Ballas and Margulis prior to the latter's execution. You finally get to meet the Lotus expecting a heartfelt moment between mother and child, only for Ballas himself to appear and she ''willingly'' followed him to a mysterious portal. All the Tenno now has is her discarded helmet, and the player is left with an extremely unsettling mix of confusion and abandonment.]]
** [[spoiler: After the Apostasy Prologue is completed, a holographic copy of the Lotus (or more accurately, Ordis posing himself as the Lotus) takes over the role as the Tenno's MissionControl until Ordis can discern the original's location. The replacement Lotus looks, talks, and acts ''exactly'' like the original... except she glows an ominous purple and her dialogue is often interrupted by static. Any player who has played the game long enough will almost definitely find this incredibly jarring after being used to the original's voice for so long. A constant reminder that NothingIsTheSameAnymore.]]
* The Sacrifice. [[spoiler: You get to ''be'' Excalibur Umbra, immobilized and unable to speak, only wheeze in rising panic and anger, ''as it's transformed into a warframe from an invalid Orokin'', watching four IV bags slowly draining into your body, all while having two conversations with Ballas - one audible one where he's having a pleasant chat about how you're going to be "healed" soon and would you like to play a game of Go? It's your favorite. The other, psychic one has him casually threaten you for interfering with him, announces that the IV bags are full of ''Infestation'', and tells you that for every piece he wins, he's going to kill one of your children. All while one of your Dax sons is sitting next to the two of you. ''Then'', once the transformation is completed, Ballas has ''Umbra'' kill your Dax child ''for'' him! On top of that is the very end - you finally see your surrogate mother again. She's transformed back into her Sentient form. The Lotus is gone; there is only Natah]].