History NightmareFuel / Warhammer40000

* '''Illuminor Szeras''': The Necron Cryptek behind Biotransaference, Szeras is repulsed and hated even by other Necron overlords and phaerons who are already mad warmongers themselves and there is a good reason behind this disgust. Szeras is a MadScientist expert in biology that seeks the cure of Biotransference, by turning the entire Necron race into energy gods, for this, Szeras has been experimenting with several living things in such ways that it would make a Drukhari actually have nightmares. Szeras is one of the few beings that managed the afromented Drukhari pale of horror, make Orks beg for death and break the will of Space Marines. His looks are also very unnerving, a giant one-eyed Necron with four arachnid legs instead of the usual two or levatating like other crypteks and two pairs of arms, one of them hiding a device that can destructure completely an object, or more commonly a living being. It has been said that when he experiments on his test subjects, he doesn't use anaesthesia because he wants to see how the living reacts to the painful changes of his experiments and if the poor subject screams too loud he simply turns down his auditory receptors so he doens't have to hear it all the time. His model shows him removing with the mentioned device, the flesh of a poor soldier who is clearly in pain. In WesternAnimation/{{Pariah Nexus}}, we get to see a glimpse of his atrocities on some human captives...

* Imotekh, the Stormlord is the phaeron of the Sautekh Dynasty, one of the biggest and most influencial dynasties of the galaxy. Imotekh is known for many things, such as being a master tactical genius that rivals that of the Primarchs and a force to be reckoned with in battle, having bested High Marshal Helbrecht and cutting his right hand as permanent reminder of his defeat. He caused the destruction of a whole dynasty, the Khuvu to such a degree that only a saying remains to remind their existence: "gone like the Khuvu". This was well before Imotekh went through Biotrnasference and being upgraded into a Necron with higher thinking processing. After awakening from his sleep, Imotekh executes the overlords that were fighting for the throne of the Sautekh Dynasty and becomes the new Phaeron, bringing conquest where he goes and expanding his territory in the galaxy.

* The Orks - the most violent, belligerent, and brutal species in the galaxy - and the Eldar - possessing psychic might enough to hit the Necrons were it hurts - were both specifically designed to destroy the Necrons. ''They failed.''

*

** [[SerialEscalation And then]], there are the mortifiers. If a Sister falls from the path of Repentia, a last chance at redemption achived by fighting the enemy in nothing but rags, even so much as to flee from battle, they are placed in the worst of prisons: the mortifier. A mortifier has all the benefits of a penitent engine, with added nightmare fuel. Along with pain amplifiers, metal rivets are driven into the wayward Sister's body, and a soundproof hood is placed over her head so she can never hear any words of praise, hoping to fight hard enough that they may somehow be redeemed in death. Repentia who actively betray their orders on top of showing cowardice are instead placed on Anchorites, which has all the devices of a Mortifier but placed in a coffin-like tank similar to a dreadnought. Deaf, blind, and aware only of their constant suffering they will fight over and over until they finally collapse, unleashing a final storm of devastation in realisation that their soul will soon be taken by the Warp, desperately begging for forgiveness that may or may not come.

* Here's a quote describing the Aceptus Mechanicus' Battle Servitors:

** One of his norotious deeds include, after taking over the planet Boras Minor, he orders every girl under 12 years of age be taken as his slave. And GW never specifies why, leaving it up to you to fill in the blanks.

* How do you keep the average Guardsman fighting the unknowable terrors of the Galaxy without running for their lives? Put something equally terrifying behind them: the Commissar. Acting as elite political officers for the Imperial Guard, these ruthless disciplinarians are tasked with upholding troop morale by any means necessary. They will show absolutely zero hesitation in putting a bullet through your head for displaying the slightest cowardice. While there are are inspiring and genuinely altruistic Commissars in the vein of [[Literature/GauntsGhosts Ibram Gaunt]] and Literature/CiaphasCain (HERO OF THE IMPERIUM), the majority are cold-blooded tyrants who can (and will) execute whole squads for even minor transgressions.

* A lasgun is considered to be, more or less, a slightly better modern day assault rifle. A flak vest is considered to be roughly the same as combat armour worn by most modern day advanced troops. And Imperial Guardsmen die in ''droves''. However, these are by no means weak equipment; the Lasgun is many time stated to be able to completely destoy a slab of cement with a single shot. By modern standards, it would be the equivalent of shooting with an automatic, recoil-less, 50. anti-armor rifle with unlimited ammunition that could destroy a modern battle tank in a single shot. An Imperium Flak Vest is better than modern day combat armor since it's stated that they're capable of withstanding light machinegun fire, which is already way better than the bulletproof vests that modern forces use that only reliably stop pistols and shotguns. It's just the invaders are often way stronger and/or smarter than those of mere mortals.

** There is a short story collection called ''Into the Maelstrom''. In short, a Space Marine Librarian (pysker) is placed undercover into the titular Maelstrom, the flagship of a Chaos Lord to find out where the lord will attack next. After he is finally given the information, he reaches out and informs the friendly troops of where the attack will be. At that point, he is captured, told that his information is fake, and he's just signed the death warrants of a dozen planets and billions upon billions of humans. After he gets knocked out he wakes up cloaked in darkness. Tubes running through his body. He tries to reach out with his psychic powers, only to find them blocked. [[AndIMustScream He then realises that he's been hooked up to a dreadnought sarcophagus]], which hasn't been attached to one of the machines. The sarcophagus can keep a person alive for near-eternity, and never has to be hooked up to an actual dreadnought machine.

* And '''Kharn''', nicknamed the Betrayer, is probably the most batshit AxCrazy of of them all. Here is the man who, in a fit of anger, ''singlehandedly shattered his own Legion's capacity as a fighting force with nothing but a flamethrower''. The game reflects this - he's just as likely to go bonkers and start hacking apart his own men if he feels like it. You have been warned.

* '''Literature/BlackLegion''' are the apex of this. Because they are ''all of the above''. The rampaging Khornate psychopaths? They have those. The sadistic Slaaneshi cultists? They have those. The silent, decaying infected Nurglite monsters that look like zombies in power armour who cheerfully declare you will be happy in the Plaguefather's embrace as your skin melts away? They have those. The manipulative and diabolical Tzeentchian sorcerers and piles of of dust in animated armour? They have those. The sadistic Raptor cults and terror obsessed maniacs? They have those. The utterly selfish and uncaring siege masters whose only values are being able to identify what is useful to them and for how long? They have those. The fanatical Dark Apostles? They have those. They have access to every single horror in the Chaos list and then some. The Black Legion has given up any identity other than their dedication to the destruction of the Imperium in favor of a new domain for humanity where the Dark Gods are the objects of worship.

*** The good part? All of of those good people sacrifice their lives willingly. They follow the Imperial Cult, the religion created around being the martyr for the sake of Imperium. Oh, wait, that's the bad part. [[ButThouMust And yet they still must]]. ''That's'' [[CrapsackWorld how bad their universe is]].

** And yet, despite all of the above, some are still brave (or insane, depending on who you ask) to try and board these things. Why, you ask? You see, these ships contain ancient technology worth literal planets to the right buyer or of immense value to one's given faction, therefore many adventurous souls try and find fortune on these derelict nightmares. It's just a matter of finding you way in and out alive, uninfected, uncorrupted and without getting betrayed by your associates, all before the Space Hulk returns to the Warp. [[ParanoiaFuel And you can't tell when it will happen.]]

* Four Gods of Chaos, countless ways to make your spine tingle. And the most horrifying thing is that they exist by [[EmotionEater feeding on the emotions of living beings]]. Living beings cannot help but feel things, and so [[AsLongAsThereIsEvil we will never truly be rid of them]], so one of the few ways to ultimately defeate them is to kill every single living being in the galaxy. This is the goal which Necrons (at least pre-retcon) want to accomplish.

** Slaanesh's realm is the Palace of Slaanesh, a series of six concentric circles each tempting you to a different sin. It does not look too overtly dangerous unlike the other Chaos God's realms, but that is the purpose -- once you fall into their traps of desire, you're dead: No outwitting Tzeentch, no outfighting Khorne, no outlasting Nurgle; deny yourself pleasure all you want, if you step foot here and do not turn back you are utterly doomed. The Circle of Avidity has mountains of gold cascading with waterfalls of sapphires, diamonds, opals, lapis lazuli, faïence and every other precious thing, but if you even try to take one scrape of gold, you will be doomed to count gold for the rest of your life, and the jewels are all inhabited by daemons that will possess anyone who dares take them. The Circle of Gluttony tempts you with a sumptuous banquet of every conceivable culinary experience, but as soon as you put one morsel into your mouth, you will not stop eating until you explode in gore. The Circle of Carnality is every piece of erotic fanfic and carnal desire come to life, morality, legality and self-preservation no object, even as you're being lured to the chopping block by daemonettes. The Circle of Paramountcy offers you roars of adulation from an inconceivably vast crowd, and the promise of absolute power over others, but play into it, and paranoia will destroy you from the inside. In the Circle of Vainglory you are tempted with your perfect self-image, where everything you ever tried to be, wished you were or secretly thought you were all along is whispered and reflected back at you in a dreamy forest landscape, but feel even the faintest stirrings of pride and this circle is your eternal prison. The last circle is a heavenly place resembling a beach illuminated by warm sunlight where all seems perfect and every moment fills you with greater bliss, but stop to savor it for even an instant and you fall into a coma to eventually die from it. You can wander here for centuries, millennia if you like, but you can't stop to enjoy the warm beach scape for a single moment without losing it all, and to make things worse, the sands there are made of the bones of the Palace's former victims. And if somehow you have an iron mind able to resist all of this and make it to the centre, where Slannesh themself dwells, congratulations, it's all been for nought: the Prince of Pleasure is a being of such surpassing beauty no mortal can look upon them without forfeiting their soul and becoming her willing and devoted slave. Hope it was worth it. If you were to ask anyone who actually succeeded at this they would probably claim it was. After all, to gaze upon perfection itself is a great honor. Or so your new mistress says.

* If you think Orks are simple-minded killing machines that know only brute force, then you're ''mostly'' right. The exception to this are Ork Kommandos, who have learned the benefits of stealth, subterfuge, guerilla tactics and espionage. Some of them can even ''read.'' All traits considered "un-Orky" by the rest of their kind. And the rest of humanity. One quote describes a group of Guardsmen being executed for cowardice and incompetence for reporting sightings of these unusual assassins.

** Popular portrayals of Inquisitors show them as completely uncaring and cruel when it comes to their methods, but a few tidbits of lore hint that many of them are consciously aware of their actions and the consequences thereof, for both the population and themselves. The Inquisitor who held off Hive Fleet Leviathan was eventually stripped of his rank, branded a Radical and potentially later killed as a heretic, as well as pitted the Orks against the Tyranids knowing full well that the victor rising from the conflict will be greater than the sum of the combined might of the two armies. He knew that this would ultimately cost him his life, his reputation and the lives of millions. But his actions is implied to have saved billions by diverting the attention of Leviathan so the Imperium can regroup and form a more lasting strategy.

* Their method of interrogation would give Jack Bauer night terrors. They engage in nine "actions" designed to get the desired information, in increasing order of pain and suffering. The first action is simple verbal interrogation. The second is ''a description of the next seven actions'', which get progressively more painful/invasive, until the ninth action is undertaken, involving all manner of torture performed with the sole intent of causing grievous physical and mental agony, with verbal interrogation to follow if the subject survives long enough to spit anything out. Many people break at the first action (given the Inquisition's reputation), and relatively few people persist past the second. The ninth action is simply giving the stubborn bastard a horrible, horrible death over months just to spite them for daring to not break.

** Roboute Guilliman's encounter with his father. He's been wounded by Mortarion, his very soul dying from the Godblight. In desperation, he calls on his father to save him. The narration of being in the presence of the God-Emperor would not be out of place describing an EldritchAbomination.

* '''Literature/WordBearers''' are the Imperial zealots with [[ReligionOfEvil all that fanaticism turned to the Dark Gods]]. And they're the ones who kicked off the Literature/HorusHeresy - in other words, the entire fucked up state of the 40K universe? Lorgar's fault. '''The entire hell-universe that would give Creator/HPLovecraft night terrors is Lorgar's fault'''. Even the ''Imperium's'' current state is Lorgar's fault, because he wrote the original Lectitio Divinitatus tract slash holy book.

** As it turns out, their motive itself reveals some added horror--it was revealed to Alpharius that if Horus were successful, humanity would have been wiped out within two generations, but Chaos would ultimately be broken. If the Emperor won, however, he would be trapped within his own body on a golden throne, and humanity would stagnate and decay over the course of the next 10-20 millennia, enabling Chaos to overrun the entire universe. [[DoomedByCanon Welp.]]
*** However, in ''Vulkan Lives'', Eldrad Ulthran, a real Eldar Farseer, indicates that it may be wrong, and that a military victory for the Imperium may be the best outcome.

** The really scary thing about the Alpha Legion is just the fact that [[PunctuatedForEmphasis they. Are.]] '''[[WeAreEverywhere Everywhere.]]''' Let's talk the Night of the Thousand Rebellions: they made the ''entire'' Segmentum Pacificus (''that's roughly 15% of the whole Imperium'') secede by launching cultist uprisings across hundreds of thousands of worlds which all occured simultaneously. Even the Lions Defiant Space Marines found themselves battling Alpha Legion forces on their own homeworld. The Alpha Legion are also the people who hypno-brainwash the natives of Astartes recruiting worlds and then trigger the unwitting recruits to turn on their own brethren just in time for an attack on their fortress-monastery. Oh, and they also have a nasty tactic of [[DressingAsTheEnemy directly infiltrating loyalist chapters]] and using Imperial battle cries to throw Imperial forces off. ''Just how do you fight an army that operates like this!?''

* You know what's really freaky? So many named characters of the Chaos Space Marines were around during the Horus Heresy. Which means the Emperor built his Empire with these psychopaths, many of whom willingly sold themselves to Chaos. [[GoodIsDumb The Emperor, humanity's greatest hope and salvation, was an incredibly]] HorribleJudgeOfCharacter.
** Another, not exactly more reassuring, theory is that he was, in fact an incredibly good judge of character (of course, character seems to have had little to do with it, considering they were created to lead, not raised to). He surrounded himself with humanity's best and brightest. And it still wasn't good enough.