%% When adding examples for rules and other information specific to a limited number of editions rather than the game/setting as a whole,
%% please note which edition is being referred to.
In ''TabletopGame/Warhammer40000'', while the present-day [[Characters/Warhammer40000Imperium Imperium]] consists of a large number of factions, the following are the most well-known.

!!Factions with their own pages:

* [[Characters/Warhammer40000Astartes Adeptus Astartes]][[note]]Also known as the Space Marines[[/note]]
* [[Characters/Warhammer40000ImperialGuard Astra Militarum]][[note]]Also known as the Imperial Guard[[/note]]
* [[Characters/Warhammer40000Sororitas Adepta Sororitas]][[note]]Also known as the Sisters of Battle[[/note]]
* [[Characters/Warhammer40000Inquisition The Inquisition]]
* [[Characters/Warhammer40000Mechanicus Adeptus Mechanicus]]

!!Other factions


[[folder:Adeptus Arbites]]
[[caption-width-right:232:Ego legis sum.]]

->''To serve the Emperor. To protect His domains. To judge and stand guard over His subjects. To carry the Emperor's law to all worlds under His blessed protection. To pursue and punish those who trespassed against His word.''

The Adeptus Arbites are the enforcement arm of the Adeptus Terra. It is they who ensure that Imperial laws and Administratum decrees are followed, and most importantly, that the Imperial Tithe is met. Most Imperial worlds of any significance at all will have an Arbites precinct house somewhere, and larger worlds will have several. Local crime is beneath their general jurisdiction (that falls to local planetary law enforcement) but they help track crime that spans multiple worlds and violates laws from authorities beyond that of the local government. When rabble-rousing citizens get in the way of the Imperial tithe being fulfilled, the Arbites are summoned to break them up and suppress riots. If it goes so far that a planet goes into full rebellion, the Arbites are the ones expected to be a loyalist holdout, sealing their precinct houses for siege and getting the message out to the wider Imperium.

The Adeptus Arbites have never had an officially published codex book, only unit information and models to be used as allies for other Imperial forces in early editions of the game. Various unofficial army lists have been released over the years and some units equipped with carapace armour and shotguns, such as Astra Militarum Veterans and Inquisitorial Acolytes, have been used as count-as Adeptus Arbites models but for the most part they are almost never seen in the core ''Warhammer 40,000'' game itself despite being relatively well represented in the background material. Adeptus Arbites forces and characters have however made limited appearances in [[GaidenGame spin-off games]], such as ''TabletopGame/{{Inquisitor}}'' and ''TabletopGame/{{Necromunda}}''.

* AwesomePersonnelCarrier: Arbites used variations of Standard Template vehicle patterns, such as Chimeras and Rhinos. In particular, they often use the Repressor pattern of the Rhino chassis, which has an extended transport bay with additional firing slits for riot suppression. They are especially fond of these because the wide surfaces and heavy armor make it an excellent mobile blockade.
* ByTheBookCop: Arbites are selected very carefully for those who will take their duty extremely seriously, many of them coming from the same [[BoardingSchool Schola Progenium]] programs that train [[ThePoliticalOfficer Commissars]] and [[EliteMooks Storm Troopers]]. One who goes CowboyCop on them will find themselves hauled before a panel of their comrades to answer for their behavior.
* CaptainErsatz: The Adeptus Arbites owes a lot to the [[ComicBook/JudgeDredd Judges]] due to their history (Creator/GamesWorkshop once produced a Judge Dredd RPG and incorporated several ideas from the setting). They even have Executioner rounds that seek out targets just like the [[SwissArmyGun Lawgiver]] can.
* CarryABigStick: Power Mauls are common weapons for Arbiters to be equipped with, taking the form of large truncheons. They mount a power field generator with adjustable power settings. At low levels, they function as a [[StunGun Stun Stick]], while at higher levels they can [[ArmorPiercingAttack shatter armor under impact]].
* {{Expy}}: Go look up what "[[Comicbook/JudgeDredd ego legis sum]]" translates to.
* FacelessGoons: {{Invoked|Trope}} by the design of the Arbites carapace armour. They are supposed to represent the vigilance and judgement of the Adeptus Terra, and by extension, the GodEmperor himself. Thus while their mouths are uncovered so that their judgement can be heard clearly, their eyes are covered so that it is hard to tell where exactly their gaze will fall next. The overall design is meant to invoke maximum projection of implacable enforcers.
* FeatheredFiend: Grapplehawks, a kind of servitor patterned after large birds of prey. They are employed by the Arbites as a kind of aerial drone, used to fly over streets, track targets, and identify known persons-of-interest in the midst of even dense crowds. They can also be used as a form of AttackDrone, where they can dive in and use their large claws and light grav-motors to restrain a target and keep them from running to evade the Arbiters who are sure to be nearby.
* GreatBigBookOfEverything: The Lex Imperialis, also know as the Book of Judgement, is technically not a single "book" at all; rather, it is a list of every Imperial decree and judgement recorded. The definitive copy of it occupies an entire temple-complex on Earth, spread across millions of volumes. Most precinct houses will contain their own libraries of these which are cut-down versions particular to their location, and individual Arbiters themselves will have singular "field" copies for quick reference and summery. Arbiters will pour over the Lex Imperialis to determine precedents, and occasionally particularly complex cases will require a judge to pour over it for years so that when they make their ultimate judgement the precedent they set going forward is carefully considered.
* HeavilyArmoredMook: The Arbites tend to wear carapace armor, which is about the best purely physical protection the Imperium can provide short of PoweredArmor. Among the Imperial Guard, this armor is restricted to only heavy infantry or elite forces, but the Arbites mission scope requires them to be more survivable and put their own equipment at less risk anyhow.
* HomingProjectile: Arbites combat shotguns are equipped with special Executioner rounds as standard. These rare, adamantium-tipped projectiles contain sensors and a primitive robotic brain that allow it to lock onto energy patterns and seek them out with unerring accuracy.
* JaywalkingWillRuinYourLife: Whether the Arbites get involved in a crime has less to do with ''what'' the crime is than ''who'' the infraction is against. Their jurisdiction covers crimes against the Imperial Adepta, and since the Imperial Adepta is considered the mortal face of the manifest will of the GodEmperor, that means any crime committed against them is not simply ''criminal'' but ''heretical''. When it comes to such spiritual matters, there is [[AllCrimesAreEqual no recognition of the concept of "petty crime"]]. Thus a crime like jaywalking that might merit a warning at worst under most circumstances can result in a much more harsh chastisement if for example doing so forces a van bearing Administratum records to slow down in route to its destination.
* JudgeJuryAndExecutioner: On an institutional level, the Arbites are charged to hand out justice without being accountable to other local agencies, though they are expected to do so only within the strictest interpretation of law and precedent. For the most part though, these roles are divided up between members of the organization, being the role of "Arbiters" to bring in suspects and "Judges" to sentence them.
* JurisdictionFriction: Happens very infrequently, if only because the Arbites automatically override local jurisdictions, and few would dare challenge them on that. That said, it is often inverted in that Arbites are not charged to investigate lesser crimes, and it often takes pleading on the part of the local enforcement agencies to get the Arbites involved in the first place if they can be convinced that the crimes are sufficiently disruptive to the normal flow of business.
* NonLethalWarfare: While they are willing to use deadly force, their mission typically involves battering down agitating elements rather than killing them outright. Not that this makes their employment any more family-friendly, said non-lethal warfare typically involves lots of clubbing, shocking, broken bones, and chemical-burned mucus membranes.
* PoliceBrutality: The Lex Imperialis overrides any local law, which means that if an Arbiter has accused you of a crime, ''you have no rights''. Incidentally, obstructing Arbiters fulfilling their duty is a crime, so stay the heck out of their way. "Always err on the side of harshness" is sanctioned policy, after all...
* ProperlyParanoid: The Inquisition is rightly known as being the most paranoid institution in the Imperium, but the Adeptus Arbites are a close second. Their precinct houses resemble military command bunkers more than civil court houses, and their armories are stocked substantially above what is required for their nominal role of legal enforcement, even including things like anti-tank weapons. [[JustifiedTrope The justification]] for this paranoia comes when a planet falls to rebellion, and the Arbites, as representatives of Imperial authority, are rightly identified as obvious symbolic and practical targets. In such instances, the Arbites are expected to brace for a siege and hold out until relief forces can arrive from off world, and this is where all that paranoid preparation pays off...
* RobotDog: Cyber-Mastiffs, a kind of servitor made from canines. They are used to help Arbiters hunt down hiding criminals, where their robotic components make them more reliable, more durable, and better trackers than their purely organic counterparts.
* ShieldBash: Arbites often wield suppression shields for this very purpose. In addition to [[LuckilyMyShieldWillProtectMe functioning as personal protection]], the suppression shield contains [[StaticStunGun an electrical discharge unit that can incapacitate anything]] struck by (or striking) it.
* ShotgunsAreJustBetter: Shotguns are a common piece of equipment for Arbiters. Mainly because most of what they go up against are expected to be more lightly armed and armored than them, but also because a shotgun provides a great deal of versatile utility with different kinds of specialized shells.
* StateSec: To a lesser degree, but greater visibility, than the Inquisition. Each precinct house is equipped to fight a small war, with vehicles, weapons, and barracks housing the Arbiters to use them. They even have a few of their own space ships, though these are (relatively) small patrol cruisers used for things like customs enforcement. In cases of rebellion these are expected to be the last Imperial strongpoints, and are meant to be held for the years it will take reinforcements to arrive.

[[folder:Adeptus Astra Telepathica]]

The Adeptus Astra Telepathica are the branch of the Adeptus Terra dedicated to the recruitment, training and control of those possessing psychic abilities. To fulfill this role, the organisation is divided between the recruitment arm, known as the League of Black Ships, and the training institution known as the Scholastia Psykana. The Adeptus Astra Telepathica is one of the most important in the entire Imperium, for they not only train the battle psykers that fight for the Imperiumís armed forces, they also provide the Astropaths who make interstellar communication possible and those unfortunates whose fate is to be sacrificed to the Golden Throne to maintain the life of the GodEmperor of Mankind. In recognition of their importance, the Master of the Adeptus Astra Telepathica is one of the permanent members of the High Lords of Terra.

Although it has been a part of the ''Warhammer 40,000'' background since the 1st Edition of the game, the Adetus Astra Telepathica has never been an independent force on the tabletop and instead have been counted as Imperial Agents alongside the Inquisition and Officio Assassinorum[[note]]during 2nd and 7th Editions[[/note]], as well as being included as a sub-faction of the Astra Militarum.

* BlindSeer: The Soul Binding ritual that all Astropaths must undergo is extremely traumatic and although those who survive have their psychic abilities enhanced, they inevitably have their optic nerves irreparably damaged by the process.
* HumanResources: Imperial worlds' psykers are rounded up to be collected by the League of Black Ships and taken back to Terra for testing. Those with sufficient potential and control are trained as battlefield psykers, astropaths, or even future Inquisitors, while the rest are sacrificed to power the Astronomican or maintain the Golden Throne.
* SubspaceAnsible: Astropaths use their telepathic abilities to send and receive messages across the gulf of interstellar space. As such these psykers are some of the most important individuals in the entire Imperium.
* PstandardPsychicPstance: One of the three models for the Wyrdvane is standing with his hand to his temple as if focusing his power.
* PsychicPowers: As the organisation responsible for controlling the growing number of human psykers within the Imperium, many members of the Adeptus Astra Telepathica have psychic abilities, from the interstellar telepaths known as Astropaths to the more battle orientated powers of the Primaris Psykers.
* WizardingSchool: The Scholastia Psykana branch of the Adeptus Astra Telepathica recruits and trains those psykers who have the strength and the ability to serve the Imperium.

[[folder:Adeptus Custodes]]

The Adeptus Custodes (known as the Legio Custodes prior to the Horus Heresy)[[note]]Other names include: The Custodian Guard; The Guardians; Watchers of the Throne; The Thousand Companions[[/note]] are the guardians of the Imperial Palace and the Golden Throne, as well as being the personal bodyguard and chosen emissaries of the Emperor. The Custodes have been genetically engineered to be perfect warriors, second only to the Primarchs themselves, and their wargear is the pinnacle of Imperial technology.

The Custodes didn't receive official models until the end of October 2016 with the release of the [[GaidenGame board game]] ''Horus Heresy: Burning of Prospero.'' Free downloadable rules for using the models in games set during the forty-first millennium were also released at the same time and, in March 2017, they received their first official codex as part of the 7th Edition ''Talons of the Emperor'' box set. The 8th Edition rules for the Adeptus Custodes can be found in ''Codex: Adeptus Custodes'' released at the end of January 2018.

* AllPowerfulBystander: After the Emperor was struck down by Horus, the Custodes entirely committed to his protection as well as the Imperial Palace. As a result they participated little in the affairs of the Imperium as a whole although their martial prowess and influence was badly needed. Ever since Guilliman's return, the Custodes have decided to not simply stand guard but also meet any enemy that will eventually threaten Terra before they actually do.
* AnAxeToGrind: Some of them (mostly the Allarus Custodes) get to use the Castellan Axe, which is effectively a Guardian Spear that is better-suited to slashing.
* AuthorityEqualsAsskicking: Par for the course in 40k, but if you encounter a Custodian with the title of "Captain-General" on the opposing side of you...well, let's just say you'll understand what "pain" means.
* AwesomeButImpractical: Invoked in-universe. While the Custodes are undisputed badasses even by 40k standards, they are exceedingly expensive to produce. Each Custodian requires roughly the same cost as a whole ''Astartes Chapter'' and while a single Custodian is to an Astartes as an Astartes is to a Guardsman, it's simply easier to drown the enemy in corpses (this being 40k and all). Thus they are allowed to remain the Emperor's praetorian guard simply because it's not feasible to use them for any other purpose.
* AwesomePersonnelCarrier: The Custodes' standard transport vehicle is the Coronus Grav-Carrier, a strikingly-designed skimmer which possesses a degree of speed and agility far superior to what its heavy armour would indicate, and is more than capable of defending itself wth its Lastrum bolt cannon and Arachnus blaze cannon.
* {{BFG}}: The rare Sagittarum Guard are known for wielding the [[MixAndMatchWeapon Adrastus Bolt Caliver]], which allows it to be used somewhat like a [[MoreDakka Heavy Bolter]], with the addition of an [[FrickinLaserBeams Adrasite Laser]] for short-range work.
* {{BFS}}: Their Sentinel Blades are as long as their wielder is tall. And since they're OneHeadTaller than an 8-foot tall Space Marine Terminator... yeah.
* BlingOfWar: The ''standard'' Custodes' PowerArmour (seen on the picture at the right) is more blinged out than most Space Marine Chapter Masters. Their [[LuckilyMyShieldWillProtectMe Storm Shields]], vehicles and Dreadnoughts are just as incredibly ornate.
* BigDamnHeroes: Makes their official return to the battlefield in the 41st Millennium by coming to Guilliman's aid as he fights Magnus and the Thousand Sons.
* BiggerIsBetter: It's probably no coincidence that Custodes' models are taller than Terminator Space Marines, which is the largest a Space Marine will look in personal equipment, and they're pretty much unmatched in combat compared to anyone in the Imperium or anyone in very many other species around the galaxy...
* BodyguardingABadass: Custodes protect the mightiest human who has ever existed. When the Emperor was alive and healthy, this trope was in full play but since the Emperor is currently a shriveled husk depending on constantly sitting on the Golden Throne for life support, it is at least downplayed.
* ColorMotif: The Custodes were notable for their [[BlingOfWar golden, ornately carved armour]]. After the Horus Heresy, black became the Custodes color to mourn the Emperor. As of ''Rising Storm'' however, they're back in their gold armour.
* CoolBike: The Custodes "Dawneagle" Jetbike is far superior to conventional Jetbikes, with an improved design supporting not only the heavily armoured Custodian, but also a Lastrum cannon.
** While plain by comparison, the "Gyrfalcon" Jetbike is still pretty cool.
* CombatPragmatist: Custodes are versed in politicking, spycraft and even assassination; skills no self-respecting Astartes would learn.
* DependingOnTheWriter: One of the most inconsistently-written forces around. The writers can't seem to agree on how strong they are (one story sees a single Custodes take on three Word Bearers' chapter masters and win in seconds, while another loses to an unarmed and unarmoured World Eater), their physiology (varies between "size of a small Primarch", "significantly larger than a Space Marine", or "very slightly larger than a Space Marine"), or on certain other aspects of their equipment and job (their equipment is supposed to be gene-locked, so that only they can use it, but there are at least two instances of Custodes weapons being looted and used by non-Custodes warriors). Their rules finally gave us an idea on them, tabletop-wise: Normal Custodians have Weapon Skill 5, Ballistics Skill 5, Strength 5, Toughness 5, 2 Wounds, Initiative 4, 3 Attacks, 10 Leadership and a 2+ Armor save[[note]]the Shield-Captain has 1 more WS and A[[/note]], with the Adamantium Will, Bulky, Deep Strike, Fearless and Eternal Warrior special rules. Which means, tabletop-wise, Custodes can be basically summed up as "Space Marine Terminators on Crack" who are ''extremely'' difficult to put down, and model size-wise, are taller than ''Terminator Marines''[[note]]The top of the head of Space Marine in Power Armour come up to mid-chest on a Custodes, and a head of a Terminator comes up to a Custodes' chin[[/note]]. Them being so large makes sense: They'd look incredibly goofy circling the Emperor if they only came up to his waist.
* EarnYourTitle: Names are the only reward Custodes have for serving the Imperium. A Custodes with an OverlyLongName is not to be trifled with.
* EliteArmy: In the vast, dehumanizing galaxy of 40K, Adeptus Custodes have the rare privilege of being a fighter that is considered a uniquely valuable individual, and there's certainly a reason for this: According to the game rules, each one is at least as tough as an Ork Warboss, Orks of which are essentially a species of MightMakesRight.
* FantasyCounterpartCulture: If at all, this trope is downplayed to them - the Custodes' units use Greek names, but don't particularly have any of sort of traits going along with this pattern; at most, they do use tend to use pole weapons like the ancient Greeks did while the more Roman-like Space Marines will probably use a chainsword for a melee weapon.
* FeelingTheirAge: Despite their immortality, there comes a time for any Custodes when age takes its toll and the warrior isn't as good as he used to be, which means he's fractions of seconds slower or he's a tiny bit less sharp, but the Custodes prefer to let someone who's in their prime take up their duty. This Custodes then abandons his weapons and armor and becomes an Eye of the Emperor, acting as a spy and informant for the rest of the Custodes.
* GateGuardian: Only the Custodes can allow anyone in the Emperor's presence, and they're the only ones who can allow another into His presence.
* GeniusBruiser: Massive and deadly as they are, it's easy to forget that the Custodians are also stunningly intelligent and trained in things like economics, politics, and espionage, and have used these skills to avert countless plots among Imperial aristocracy on Terra that might plunge the Imperium into chaos (or Chaos).
* GoldColoredSuperiority: The Custodes are the best military force in all of the Imperium and it shows. They wear an armor made of auramite, a very rare metal which is naturally colored gold. By extension all their equipment and vehicles are gold-colored. However, the auramite can be colored, and one brotherhood within the Custodes adorns black auramite armor (albeit with golden decorations).
* GondorCallsForAid: They return to active duty at the behest of Roboute Guilliman, being seen for the first time in thousands of years on the front lines.
* HoverTank: Take a Sicaran Battle Tank, and stick it on a Land Speeder and you have the Custodes' Caladius Grav-Tank. Their "standard" AwesomePersonnelCarrier is the Coronus Grav-Carrier.
* InterserviceRivalry: Many Space Marines envy the Custodes for being so close to the Emperor.
* ItWasAGift: Each Custodian is personally given their weapon by the Emperor... at least, they were before the Horus Heresy. They've probably dropped that rule by "modern" 40k.
* MixAndMatchWeapon:
** Most Custodes, particularly the Custodian Guard, wield Guardian Spears, [[BladeOnAStick polearms]] that combine a power blade with an integrated bolter [[note]]Earlier editions differed as to the exact weapons used with some replacing the power blade with a [[{{Vibroweapon}} vibro-blade]] and/or the bolter with [[FrickinLaserBeams high powered laser weaponry]][[/note]]
** The Sentinel Guard wield Sentinel Warblades instead of Guardian Spears. These massive swords, [[{{BFS}} as long as a Custodian is tall]][[note]]Which is sizable, as they're taller than Space Marine Terminators[[/note]], incorporate a double-barrelled Bolt Caster into the crossguard that fires a hail of short range bolt rounds.
** The Adrastus Bolt Caliver, part [[{{BFG}} Heavy Bolter]], part laser gun, and is exclusively wielded by the Sagittarum Guard.
** The [[AnAxeToGrind Castellan Axe]] works like a Guardian Spear that's specialized for slashing, and is often seen in the hands of the [[BloodKnight Allarus Custodians]]. Trajann Valoris's Watcher's Axe also fits in this category, only bigger and fancier.
** The Emperor once declared that all of the energy weapons known as Adrathic Destructors, which are unique to Terra, shall be given to him under pain of death for the entire family of those who would conceal them from him. Only members of the Imperial Household may carry them. Custodes are part of the Imperial Household. Ergo, only Custodes may use Adrathic Weapons, the most powerful in the galaxy pound-for-pound. They are often integrated into two-handed blade weapons, or the arms of Dreadnoughts.
* OneHandedZweihander: Those Sentinel Warblades that they wield, which are described as "daunting greatswords"? Yeah, Custodes don't even bother using two hands to hold them.
* PowerArmor: Much like the Astartes, the Custodes have this...and of course, they have their own Terminators. Said Terminators come in two flavors:
** Aquilon armor is like standard Terminator armor, only significantly better.
** Allarus armor mounts a teleporter, and is worn by the [[BloodKnight Allarus Custodes]]
* PraetorianGuard: The Custodes defend the Emperor even long after his internment in the Golden Throne. Even before that, they were bodyguarding the Emperor when in battle.
* PromotedToPlayable: The Custodes received rules for the first time in 2016, 29 years after being introduced in Rogue Trader.
* ShirtlessScene: In the first edition, the Custodes abandoned armor after the Heresy. They're once again wearing their golden armor as of ''Literature/TheBeastArises'', and their 7th Edition models are fully armoured.
* SmallRoleBigImpact: The Custodes singlehandedly ended the Age of Apostasy first by talking the Brides of the Emperor into turning against Goge Vandire, then convincing (or scaring) Sebastian Thor into becoming the new Ecclesiarch.
* SoldierVsWarrior: The Warrior to the Soldiers of the Space Marines and Imperial Guard. Custodians have genetic kinship with each other in their formations, but they are much more solitary than the Astartes or Guard in terms of their actions as a military function. Also, their individuality is reinforced by the rigor of their creation process and the lack of mass production it involves, in contrast to the creation of Astartes or induction into the Guard. Notably, however, is that the Adeptus Custodes are still able to fight and operate in perfect coordination, beyond even the most advanced and skilled of Astartes, but this is simply because they are ''that much better'' in terms of physical and mental ability and their wargear. What an Astartes would take decades or centuries to learn through training and experience comes entirely naturally to a Custodes.
* StealthExpert: Despite their size and standard shiny equipment, Custodes are also accomplished infiltrators. Several Custodes are constantly trying to infiltrate the Sol System, Terra, the Imperial Palace and eventually the Throne room in what is called "Blood Games" in order to test their defence systems and seek out any weak point so they can be corrected at once.
* SuperPrototype: Of the Space Marines, only the Primarchs are more powerful than the Custodes.
* UndyingLoyalty: To the Emperor, whose corpse they still guard. In fact, they refuse to recognize any authority other than the Emperor, unless He has explicitly empowered another, which is the only way their ranking system works. Notably, they are the only division of the Imperium not answerable in any way to the Inquisition, due to the fact their authority comes directly from the Emperor himself. It wasn't until Robute Gulliman entered the Emperor's throne room and emerged again that the Custodes decided that they were done with simply guarding the Emperor and set out to do his will upon the galaxy.
* WalkingTank: Like the Astartes, the Custodes have access to Dreadnoughts, most of which are the much-vaunted Contemptor-pattern with fittingly up-scaled weaponry.
** The Contemptor-Galatus Dreadnought gets a sword with a built-in [[KillItWithFire flamethrower]] and a shield.
** The Contemptor-Achillus Dreadnought gets the [[BladeOnAStick Dreadspear]], which is an up-sized Guardian Spear with a built-in laser gun. In addition, they come with a variety of [[ArmCannon wrist-mounted guns]].
** This is taken UpToEleven with the Telemon Heavy Dreadnought. It's so big that it can mount the [[GatlingGood Arachnus Storm]] [[FrickinLaserBeams Cannon]] or the [[{{BFG}} Iliastus Accelerator Culverin]] in one arm, and a PowerFist with built-in weapons on the other.
* YinYangBomb: Have both (super-)Astartes enhancements and Assassin training; Space Marines and Assassins are elsewhere said to occupy opposite ends of a spectrum ranging from "honor and glory" to "stealth and secrecy".

[[folder:Imperial Fleet]]

->''If the Adeptus Astartes are the Emperor's wrath, and the Imperial Guard His hammer, then His Holy Navy is His mighty shield.''
-->-- '''Cardinal Kregory Hestor'''

The Imperial Fleet controls all the shipping and transport between world and from a planet's surface to orbit. As with most Imperial organisations, the Imperial Fleet is split into a number of different branches with two of the most important being the Imperial Navy and the Aeronautica Imperialis.

For all the size of the Emperor's vast armies and the prowess of his Angels of Death, the Imperial Navy is what gives the Imperium of Man the force-projection it needs to be an interstellar superpower. Made up of multiple fleets of Warp-capable grand ships, each with lengths measured in kilometers and with crews that reach into the thousands on even the smallest of them, few powers can match the Imperial Navy when it musters in force. But because even the smallest ship can only be produced at relatively high tech worlds with reliable access to material and they can take anywhere from decades to centuries to construct, the vast might of the Imperial Navy is stretched thin across the galaxy, patrolling Warp routes and escorting the interstellar transportation that countless worlds rely on simply for survival. When the Imperium goes crusading, the vessels of the Imperial Navy transport and escort the vast numbers of ground forces the Imperial war machine can bring to bear, supporting them with literal walls of guns so numerous and massive that not even a Titan war machine could mount them.

Although their focus is primarily on the sea of stars, the Imperial Fleet are also responsible for deploying the Imperium's more conventional aircraft. The Aeronautica Imperialis is the branch of the Imperial Fleet responsible for operating these atmospheric craft, providing everything from the airborne transport of elite troops to pinpoint airstrikes and carpet bombing of enemy positions in support of the forces of the Astra Militarum.

The Imperial Navy itself is not often represented in the core ''Warhammer 40,000'' game, as that focuses on ground engagements and the Imperial Navy is by its own mandate limited in its capacity to project force there. However, it is well represented in the fiction, as well as in Specialist Games like ''TabletopGame/BattlefleetGothic''. The Imperial Fleet's Aeronautica Imperialis meanwhile was originally spun-off into its own small sub-faction in 7th Edition's ''Codex: Imperial Agents'' and had their 8th Edition rules included in the ''Index: Imperium 2'' book released in June 2017. The majority of Aeronautica Imperialis forces in ''Warhammer 40,000'' however are produced by the Games Workshop's Forge World department and their rules are included in the ''Imperial Armour - Index: Forces of the Astra Militarum'' book.

* BadBoss: {{Downplayed|Trope}}, in that, like [[Creator/NiccoloMachiavelli Machiavelli]]'s [[Literature/ThePrince Prince]], an Imperial Navy captain will generally prefer to be both feared and respected, but ultimately the Navy needs its captains to be feared more than they need them respected. So much so that the lives of a few ratings are considered expendable if it means enforcing appropriate discipline on the rest.
* BoardingParty: The Imperial Navy can and does engage in boarding actions, with teams of Naval armsmen piling into assault boats to raid enemy ships as they pass by, or even attaching grapnels on kilometer-long chains and winching the ships into a forced dock with each other. Some of the boarding parties might even teleport to an enemy ship if they are (un)lucky enough to be on a ship with a functional teleportarium.
* BoardingPod: An alternative to the assault shuttles and teleporting is the boarding torpedo, launched from ships equipped with torpedo tubes. In many ways this is the most dangerous method of conducting a boarding action, as the torpedo has limited ability to maneuver to evade interception. If it misses the target it is likely to go off into deep space with every soul still trapped aboard, and even when it hits its target there is no easy line to retreat to the mothership if things go poorly for the boarders. However for all that, it is one of the quickest ways to get boarders to their target.
* BreakOutTheMuseumPiece: Imperial Navy Reserve Fleets consist of many old and obsolete classes of ship that are no longer used in regular Navy Fleets, including many that are more commonly seen fighting with Chaos Fleets such as the Repulsive-class Grand Cruiser and the Carnage-class Cruiser. The Imperial Navy is reluctant to use these fleets to their ships lack of regular maintenance and their hastily assembled crews have a tendency to be unreliable at best, if not outright mutinous.
* CoolButInefficient: Imperial Navy spaceships are hypertech vessels decorated with gargoyles and other morbid sculptures on the outside (which are completely functional, they usually hide weapons or other projectors, as well as that they keep out the Warp, if you believe in their capability to do so...), and crewed mostly by throngs of press-ganged deck-hands that must do most everything by muscle power.
* CoolSpaceship: Every ship in the Imperial Navy is a precious artifact, their outer hulls fitted with crenelations, gargoyles, and other baroque decorations that make them resemble starfaring battle-cathedrals.
* CyborgHelmsman: Many officers of the Imperial Navy are so heavily augmented they're often described as being more part of their ships than autonomous beings.
* FixedForwardFacingWeapon: Due to the necessity of accelerating the shells along the length of the ship, the Nova Cannons used by some Imperial capital ships are always mounted on their armoured prow.
* FlauntingYourFleets: Actually part of the Imperial Navy's mandate. Standard operating procedure for ships on patrol duty is to stop by infrequently visited worlds in their path to "fly the flag" and remind those worlds the grandeur of the support they are entitled to under the Pax Imperialis... and of what they would be up against should their faith stray.
* JumpedAtTheCall: Despite the common practice of {{Press Gang|ed}}ing to fill required crew numbers, the majority of ratings on Imperial Navy ships are willing volunteers. Partly this is because life aboard a warship is hardly any more harsh than [[CrapsackWorld some of the places they might be recruited from anyway]], and partly because the Imperial Navy actually pays its ratings substantially well. Of course, the reason the Imperial Navy can afford to be so generous is because they know [[WeHaveReserves barely half the ratings will survive long enough to collect their payout...]]
* LostTechnology: Archeotech, technology from an earlier era that the Imperium has forgotten the secrets of manufacturing, is a matter particularly important to the Imperial Navy. Many of their oldest ships contain irreplaceable advanced systems, and each is a force-multiplier compared to more modern equivalents if such an equivalent even exists anymore. The Navy will often go out of its way to retrieve the wrecks of older ships just to plunder such components and use them in ships currently in service, even risking investigating and breaking pieces off of space hulks to get at them.
* MachineWorship: Every ship has a staff of Tech-Priests to maintain the more critical advanced systems, such as the Warp engine and the plasma drives, servicing those components with all appropriate ritual. However in a more general sense, as their brand of techno-animism is Imperium-wide, and that ships being as vast and complex machines as they are, virtually all look upon the ship itself as being a holy thing. Any given ship will have an operational lifetime far longer than any of its crew, and the battle honors it accumulate and its mechanical quirks are seen to be indicative of the strength of its machine-spirit. Powerful old ships are regarded with the same veneration that Imperial citizens regard living saints.
* OfficerAndAGentleman: Officers of the Imperial Navy are often from highborn stock on their respective homeworlds, sometimes being the product of [[RoyalsWhoActuallyDoSomething entire dynasties of servicemen]].
* OrbitalBombardment: One of the biggest assets a Navy can bring in support of a ground engagement. However, such "orbital artillery" is both [[ThereIsNoKillLikeOverkill extremely overpowered]] for most planetary targets and [[UnfriendlyFire extremely inaccurate]]. This typically relegates the use of such power to carefully considered strategic situations to avoid excessively damaging targets the Imperium would benefit from taking relatively intact. In-game, this inaccuracy is reflected in the Orbital Bombardment ability of Space Marine Chapter Masters, which always scatters the full distance rolled instead of subtracting the Chapter Master's Ballistic Skill.
* PressGanged: A common method for fulfilling the Imperial Navy's enlisted personnel needs. Since there is rarely any return journey for someone aboard ship, the conditions are extremely harsh, and the common citizens of the Imperium are often taught to fear and shun warp travel, impressment is something the Imperial Navy frequently relies on. When arriving at a heavily populated place like a hive world and the need for new recruits is high, they will often lean on the local enforcers to institute a crackdown, with the sentences being waived for Naval service.
* RammingAlwaysWorks: Well, not always, but with a wedge-shaped prow that is a solid plate of armor thirty meters thick, Imperial Navy ships have a good chance of pulling it off if they can get close enough. Even when not used for ramming, the heavily armored prow is designed to have a psychological effect on those commanding such ships, as it encourages them to keep the ship pointed ''toward'' the enemy up until the moment they are ready to unleash a full broadside.
* SchizoTech: In full force. When the Imperial Navy was started (as part of the Imperial Army during the Great Crusade) it had powerful and advanced ships. But as entropy and battle have taken their toll, and the knowledge of how to construct much of that technology has been forgotten, even those older ships would sometimes end up replacing a critically damaged advanced system with a much lower tech version, and newer ships rarely get anything so advanced to begin with. This leads to situations where a ship might be capable of traversing the Warp, but have cannons that fire multi-ton shells which are loaded by hand by teams of laborers pulling on chains. The hand-loaded guns are an interesting situation, as the Imperium still possesses the technology to reload starship weapons without relying on manual labor--the ships of the Mechanicus are all equipped with autoloaders instead. Of course, in the Imperium having the technology to upgrade something and the will do it are very different issues. It can be safely assumed that Mechanicus ships have enough Tech-Priests and highly-trained menials aboard to carry out the regular maintenance rituals macro-cannon autoloaders require, while Imperial Navy ships depend on [[PressGanged sometimes unwilling crews]] who have minimal technical training and require systems that can be operated and maintained with relatively unskilled labor.
* SpaceFighter: Some Imperial Navy ships mount launch bays for these. Exact loadouts can very depending on the ship and the local manufacture, but the best known are the Fury interceptors, the Starhawk bombers, and the Shark assault boats.
* SpaceIsAnOcean: The Imperial Navy has a virtual monopoly on warships capable of sailing the "[[HyperspaceIsAScaryPlace sea of souls]]" which ensures that any system that goes rogue does so in isolation.
* SpaceNavy: The Imperial Navy proudly embraces every trope associated with sea-going navies in recent history and puts them in space aboard miles-long starships covered in baroque bling. It has broadsides, boarding parties, ships ramming each other, naval ranks and and traditions, crews of press-ganged sailors, and everything else you would expect from how SpaceIsAnOcean.
* SpacePeople: Due to the mixed-sex nature of most crews and the centuries-spanning service histories of most starships, crews being made up in good part of multiple generations of "voidborn" is not uncommon. Many starship crewmen have never set foot on a planet in their lives, and most have no wish to. It is also not uncommon for there to be entire tribes descended from lost crew members inhabiting forgotten and abandoned decks.
* SpacePlane: Although primarily intended for atmospheric operations the Thunderbolt and Lightning fighters, as well as the Marauder bombers, operated by the Imperial Navy are also capable of operating in a vacuum. This is mostly due to the necessity of being deployed from carriers in orbit, when ground bases are unavailable, but there are many instances where such craft have been used in space combat when dedicated space fighters and bombers were unavailable.
* StandardSciFiFleet: Fits the standard, but with the scale turned UpToEleven. Even "small" escort craft such as destroyers and frigates would match battleships in many other settings taken just on their size alone, while battleships in the Imperial Navy are kilometers long with crews over a hundred thousand strong.
* StarshipLuxurious: {{Averted|Trope}} for the vast majority of any ship, where accommodations can be described as "spartan" at best and IndustrialGhetto at worst. However, this is played very straight by a ship's command decks, where the passages are broad and tall, roofed with in decorative archways, enormous windows give vistas of the stars, and are often paneled with wooden or stone facades such that walking through them is like walking through a cathedral planetside. This is taken UpToEleven by the Navigators' quarters, which are said to embarrass a planetary govern in their opulence, and are often built into tall spires jutting from the ship so that the Navigators aboard can better see what they are doing while performing their absolutely critical task.
* ATasteOfTheLash: A common method of enforcing discipline among the enlisted personnel.
* WeWillUseManualLaborInTheFuture: Mainly because the automated systems which would otherwise fulfill those functions have long since broken down or those who known how to build and maintain them forgotten. As a result, Imperial Navy ships have huge crews of menial laborers to do everything from load the cannons to "stoke" individual valves coming from the ship's plasma reactors. Actually controlling a machine as vast as an Imperial Navy ship would either require a sophisticated artificial intelligence ([[AIIsACrapshoot which is forbidden]]) or vast numbers of people working under a single set of orders (which is not.) And of course, the bigger crew it has, the more it can continue to fight on despite [[WeHaveReserves taking horrific damage]].
* WoodenShipsAndIronMen: [[RecycledInSpace ... In Space]]! The technology and practices of the Imperial Navy heavily mirror the age of sail warfare, with ships lining up to fire broadsides, and crews scrambling to ready weapons or manually handle individual maneuvering stations to bring the ship to bare, all coordinated by officers screaming orders over the chaos.

[[folder:Knights Questoris]]

->''Fealty, Honour and Duty''

The Knights Questoris (also known as Imperial Knights) are a sub-empire within the Imperium, rulers of their own private feudal planets known as Knight Worlds. Closely allied to the Tech-Priests of the Adeptus Mechanicus, the Nobles of these Knight Worlds pilot massive mechanized war machines, known as Knights, which are of such stature and fury that a single one can change the course of a war. Bound by ancient oaths that tie them to the Imperium, the Knights seek to fight the enemies of Man wherever they may be found. Numerous marks of Knight exist, with the most common being the [[JackOfAllStats generalized]] Knight Paladin and the close range, anti-armour oriented Knight Errant.

Originally a force in the ''Epic'' scale game system, the Imperial Knights were largely confined to fluff for a number of years before they were reintroduced into the core ''Warhammer 40,000'' game in 2014. The 8th Edition of the game saw the Imperial Knights given the [[CanisLatinicus High Gothic]] name, the Knights Questoris[[note]]the previous name was kept as the Low Gothic term[[/note]], with those Knight Houses aligned with the Imperium being known as the Questor Imperialis, while those with close ties to the Adeptus Mechanicus being known as Questor Mechanicus. The 8th Edition rules for fielding Freeblades and standalone Questor Imperialis and Questor Mechanicus armies can be found in ''Codex: Imperial Knights'', released in June 2018, while the rules for using Questor Mechanicus Knights as part of a wider Adeptus Mechanicus force can be found in ''Codex: Adeptus Mechanicus''. The rules for using the older and rarer types of Knight, produced by Games Workshop's Forge World subsidiary department, can be found in ''Imperial Armour Index: Forces of the Astra Militarum''.

* AuthorityEqualsAsskicking: The most skilled and deadly Nobles can become Barons, leading contingents of Knights into battle, often getting custom Knight suits with better weapons.
* {{BFS}}: Tempest Warblades, large power blades carried by the Cerastus Knight-Castigator that can cleave another Knight in two and reduce whole enemy units to ash.
* BladeOnAStick: Some Knight variants carry Power Lances. The Cerastus Shock Lances carried by the Cerastus Knight-Lancer double as {{Boom Stick}}s.
* BloodKnight: Knights Styrix, whose machine spirits are said to have become too accustomed to the slaughters of the Age of Strife. Some Knightly Houses avoid them, finding them too uncontrollable and malevolent, while others set them loose to slaughter enemies on battlefields where subtlety isn't a concern.
* BoringButPractical: [[OverlyNarrowSuperlative By the standards of giant humanoid combat robots in the Imperium of Man, at least.]]
** The Knight suits are actually easy to mass produce and require only a single operator, as opposed to the centuries it takes for a Forge World to build even one Warhound Titan, not to mention the training the Princeps and his crew requires. This allows them to be far more ubiquitous than the larger Titan Legions, despite each individual Knight packing less firepower.
** Compared to some of the more esoteric weapons that other Titans pack (among them a missile that tears a ''NegativeSpaceWedgie'') Knight suits are armed with relatively humble battle cannons and melta cannons to battle. But while these weapons lack special rules or flair, they get the job done by [[MoreDakka simply drowning the opposition in sheer firepower]].
* BrainwashingForTheGreaterGood: The process of interfacing with a Throne Mechanicum not only imprints the Noble's personality on the Throne, it also changes the personality of the Noble: instilling strong feelings of honor and duty, a respect for order and hierarchy, and a veneration for one's ancestors. The exact reason for this is unknown, but it was most likely intended as a form of mental RestrainingBolt to help stop Nobles from going rogue.
* ChainsawGood: Reaper Chainswords, a smaller version of the kind used by Titans, which can cut through enemy bunkers with ease and open tanks like tin cans.
* CloseRangeCombatant: The Knight Gallant, armed with a Reaper Chainsword and a Thunderstrike Gauntlet, is designed to smash apart enemies at close range (other Knights have at most one close combat weapon). The downside is that it only has a Heavy Stubber or Melta as ranged support without taking Carapace weapons into account.
* DefeatEqualsExplosion:
** In their 8th Edition rules, Knights have the ''Explodes'' Ability that causes it to deal unsaveable wounds on every unit nearby when it is reduced to 0 wounds.
** In previous editions of the game, Knights were Super-Heavy vehicles, and thus if they suffered an Explodes! result from a penetrating hit, the diameter of its blast was ''15 inches'' [[note]]to put that in perspective, most vehicles' blast covered 1-6" from the edge of the hull[[/note]] and could scatter (representing the Knight staggering and falling), so it had the potential to take out a large chunk of an army if it went boom.
* FeudalFuture: Even more so than usual in the setting. Society on Knight Worlds is divided between the serf-like Drovers, who tend to herds and crops and are equipped with simple unarmed walkers; the Sacristans, a subset of the Mechanicus who look after the mecha and keep the peace between noble houses; and the Knightly Houses proper, who have exclusive access to the HumongousMecha and use these to rule their worlds, and who are sworn to a number of high lords. In turn, all the lords of a planet answer to a single Princeps or High King, who is sworn to either Mars or Terra, respectively.
* FireBreathingWeapon: The Acheron-pattern flame cannon is a massive flamethrower used by the highly aggressive Cerastus Knights-Acheron that is almost as powerful as the flamer class weapons utilized by Titans. Employed as much as a terror weapon as a weapon of extermination, Knight-Acheron are infamous for their excessive use of these weapons, reducing their enemies to ash floating through flame-scorched ruins.
* GrievousHarmWithABody: Knights equipped with Thunderstrike Gauntlets can pick up defeated enemies and hurl them at opponents, causing a nearby enemy unit to suffer wounds if the Knight kills a monster or destroys a vehicle.
* HonorBeforeReason: The Code Chivalric followed by Nobles demands certain protocols of behavior and rules of engagement that must be adhered to, regardless of circumstance. Since the Becoming ritual undergone by every Noble essentially ''programs'' adherence to the Code Chivalric into them, they could literally be said to default to their code of honor as a behavioral guide before their reasoning mind even has a chance to address the problem.
* HumongousMecha: Not quite as gigantic as the Titans fielded by the Adeptus Mechanicus, but still significantly larger than the [[MiniMecha Sentinels]] used by the Astra Militarum.
* KnightErrant: Individual Nobles may at times detach themselves from their Knightly Houses entirely due to being dishonoured, shunned or otherwise made unable to continue life within the Household. These knights, known as Freeblades, break out on their own with only a handful of retainers to maintain their armor and opt to either quest across the stars fighting the enemies of the Imperium or settling down and protecting the settlements on whichever worlds they end up on. There is also a pattern of Knight called a Knight Errant, which is armed with a Reaper Chainsword and a Thermal Cannon; if one of those should become a Freeblade, it becomes a KnightErrant Knight Errant.
* LightningBruiser: Knights Lancer, a rare type of Knight suit notable for being much faster and more powerful than other kinds, in addition to having [[BladeOnAStick better]] [[BoomStick close-combat]] [[LuckilyMyShieldWillProtectMe weapons]]. The main reason they're only used as scouts and flankers instead of being the default type is because they're too difficult to manufacture to make in large numbers.
* LowCultureHighTech: Even by this setting's standards. The Knight Worlds are generally on a medieval tech level, apart from the Knights and any other toys the Adeptus Mechanicus feels like giving the local rulers.
* MightyGlacier:
** In early editions of the ''Epic'' game system, the heavily armed and armoured Knights Crusader and Knights Castellan were considerably slower than other classes of Knight but had improved armour saves and were equipped with Quake Cannons, massive weapons normally mounted on full scale Titans. In the 8th Edition ''Warhammer 40,000'' rules, Dominus-class Knights (represented by the Knight Castellan and the new Knight Valiant) have a slower Movement speed, more Wounds, and more firepower than the "standard" Questoris-class Knights (including the new version of the Knight Crusader).
** The Acastus Knight Porphyrion is one of the largest Knight suits in existence, being nearly as large as the Scout Titans of the Collegia Titanica. These massive Knights are able to unleash massive amounts of firepower that can destroy almost any target and, in the 8th Edition rules, although they have the same armour save as other Knights the Porphyrion has a higher Wounds characteristic. This massive weight and power results in the Propyrion having the lowest Movement characteristic of any Knight however.
* PlasmaCannon: Meltaguns and the larger Thermal Cannons.
* PowerFist: Thunderstrike gauntlets are massive power fists that can cause shockwaves just by being clenched into a fist. Some classes of Knight, such as the Cerastus Knight-Acheron, are armed with a Reaper Chainfist that combines a power fist with a [[ChainsawGood powerful chainblade]].
* SwordAndGun: The Knight Paladin, Knight Errant, and Knight Warden all have a [[ChainsawGood Reaper Chainsword]] mounted on one arm and a gun on the other in their default loadout.

[[folder:Mutants and Abhumans]]

->''Twisted flesh, twisted soul.''

The Imperium does not simply worship the Emperor, but also the holy human form. Part of the Imperium's UsefulNotes/ManifestDestiny states that humanity has a right to rule the galaxy. However, the simple fact is that after thousands of years on other worlds, various human populations have evolved into different types of humans. These are referred to as Abhumans or Mutants, variously; Abhumans are fairly minor, stable strains of mutation that are effectively the result of natural evolution caused by different environments, while Mutants are far more bizarre in form and stem from the wide variety of genetic degeneratives at loose in the galaxy at large -- radiation, genetic warfare, toxic chemicals, ''et cetera''. While the Imperium officially disdains them, some are useful or even necessary. In the time of the Emperor, the view of Abhumans and Mutants was more lenient, but after ten thousand years, the Imperium has taken a more draconian approach.

In the background, the most important of mutants are the Navigators, families who were genetically engineered in the distant past to navigate the Warp with psychic powers. Collectively, they form the Navis Nobilite, wealthy families who are necessary for the Imperium to survive. On the tabletop, certain Abhumans are useful to the Imperial Guard for specialist skills. Mutants, in the background and to an extent on the tabletop, are typically executed on sight for their genetic damage or kept as slaves. As a result, they are eager worshipers of Chaos, aided by the fact that Chaos tends to both cause mutation in its followers and treats those bearing mutations as being blessed by the Gods.

!!General Abhuman and Mutant tropes

* TheAtoner: Beastmen who followed the Imperial Cult were ruthless in purging the Emperor's enemies as penance for the "sin" of mutating.
* BeastMan: The ''Homo sapiens variatus'' strain of abhuman, more commonly known as Beastmen, are goat-like humanoids with [[HornedHumanoid long, curved horns]] and shaggy fur. Although some have served the Imperium valiantly as part of the Militarum Auxilia, Beastmen are still most persecuted of all the abhuman subspecies and many scholars believe they could be reclassified as true mutants.
* BodyHorror: Generic mutants. Even those who haven't been touched by Chaos can sport all manner of strange and unnatural features, including but not limited to: extra eyes/mouths/limbs, rotting flesh, atrophied bodyparts, unnaturally swollen musculature, oversized bodyparts, scales, fur, fangs, claws, slime-oozing skin, blisters and warts, tentacles... Essentially, a mutant is living BodyHorror and may or may not have {{Lovecraftian Superpower}}s as a result of it.
* ChuckCunninghamSyndrome: Originally, many Abhumans were transplants from ''TabletopGame/{{Warhammer}}'', but as time went on, they stopped being updated or even mentioned. The Squats are the most famous example of this.
* DumbMuscle: Increased size, strength and toughness at a cost of lowered intelligence is a fairly common mutation. Some, however, are bigger, stronger, and tougher than regular humans while [[GeniusBruiser being just as smart or smarter than humans]].
* EvilAlbino: Downplayed with the Afriel Strain, a failed experiment in creating non-Space Marine super soldiers. Not only are they albinos, they have horrible luck.
* ExtraEyes: They're a common mutation, and [[EyesDoNotBelongThere can turn up in the strangest places]].
* FantasticRacism: The Imperium typically takes a very dim view of mutation from the accepted norm of the "Holy Human Form", though the degree to which a typical citizen subscribes to this will vary. One major reason for this is that mutation is often a sign that one is becoming [[TheCorruption corrupted by the Warp]], potentially becoming a vessel for the Ruinous Powers. However, this hatred extends to those whose mutations are caused by more "mundane" sources, such as generations of exposure to radiation or industrial waste, leading to widespread hatred and distrust of all mutants. Since mutation can continue to appear generation after generation, killing all mutants tends to be impractical, so most are allowed to exist as an oppressed underclass, looked down upon by all.
** Abhumans are subraces of humans whose differences have manifested into stable genotypes, without the randomness seen as signs of corruption. They often suffer some prejudices related to their differences, but find a much better measure of acceptance, especially if those differences make them valuable to the Imperium in some way. Navigators in particular, while still somewhat feared, are also held in a degree of awe due to the absolutely essential role that they play in the Imperium.
* HeavyWorlder: How Ogryns and Squats came to be, even though they went in completely different directions. This was explained in older fluff as the Squats being descended from the inhabitants of mining worlds who explicitly set up their cities underground to pursue minerals and escape their worlds' toxic atmospheres, with the lack of headspace accounting for their height and the high gravity for their toughness and strength.
* HumanSubspecies: The stable abhuman strains are self-perpetuating offshoots of humanity, descended from populations of baseline human colonists in the Dark Age of Technology who had to adapt to extreme or unusual environments, such as the Ogryns descending from the inmates of high-gravity prison worlds or the Nightsiders from inhabitants of lightless planets. As such, they're no more at risk of Chaos corruption than anyone else. Doesn't stop most Imperial citizens from considering them no better than xenos or mutants, mind.
* {{Lightworlder}}: One abhuman strain, the Longshanks, have grown extremely tall and thin after millennia spent living on low-gravity planets. As a result, they are unable to endure Earth-normal gravity, and are effectively stuck on their homeworlds.
* LizardFolk: The Scalies of ''TabletopGame/{{Necromunda}}'', a strain of massive reptilian abhumans marked by scaly skin and the ability to regrow lost limbs and regenerate wounds.
* NWordPrivileges: Many refer to each other as "twists", but for a non-mutant to use that would be seen as a nasty insult.
* RadiationImmuneMutants: One of the reasons why mutants are often employed as a labor force is that they are often willing (if only grudgingly so because FantasticRacism and circumstances limit their options) to perform labor in and around whatever corrupting influence mutated them in the first place (caustic industrial chemicals, aggressive fertilizers, radiation-leaking reactors, toxin-laden mines, etc.) While they are not necessarily ''immune'' to further effects, they are already twisted beyond the Holy Human Form and a little more would hardly make things much worse for them.

!! Specific important mutants and abhumans


->''In my high seat I gaze into the immaterium and see the shadow that our own universe casts into depthlessness. This eye... this eye sees gentle flows of soul-stuff where the becalmed mind might starve to death, and tides and churns of genius and hate. The warp mocks the power of words to describe. But what I can never turn my back on is the power and the beauty of the Emperor. I see His soul shine out from Earth and His presence fill every corner of the immaterium. [...] I have known from the first time I beheld it that I could do nothing but follow that light with my life.''

The Navigators are a race of mutants that is an integral part of the Imperium's function, as their mutation allows them to actually see the fluctuations of the Warp and the light of the Astronomican, and thus guide Imperial ships (relatively) safely in Warpspace.

* ArrangedMarriage: Since Navigators can only pass on their psyker genes by procreating with other Navigators, marriages among the Navis Nobilite are arranged usually between rival houses to ensure genetic stability and as a form of alliance.
* AsskickingEqualsAuthority: When the Paternova dies, the Heirs Apparent (the most powerful Navigators of each house) become larger, stronger, and more aggressive. They then fight and kill each other for the right of Paternova.
* BlindfoldedVision: When not actively guiding a ship, Navigators will cover their ThirdEye, as [[DeadlyGaze looking into it can cause madness]]. This makes [[PowerLimiter limiting others' exposure to it]] necessary. This covering can take many forms, from a headband, to a veil, to an {{eyepatch|OfPower}}, to [[InTheHood a low-pulled hood]], or even occasionally [[ElectronicEyes a cybernetic shutter-like metallic eyelid]].
* BodyHorror: Thanks to a limited breeding pool, the possibility of imperfect genetic tampering on the part of some ancestors, and generations of necessary Warp exposure, Navigators often suffer from a variety of minor mutations. As Navigators age these mutations become more obvious and extreme, with some of them even transforming into ugly frog-octopus things. It's an accepted fact of life for them and even during the brutal inter-house coldwars both sides will respect this secret and ensure that nobody breaks the {{masquerade}}. The Emperor was aware of these mutations but decided to tolerate them.
* DeadlyGaze: Staring into a Navigator's Warp Eye is commonly said to [[BrownNote cause either insanity or death]]. No one wants to test it, and Navigators must wear hoods, scarves, or headbands of [[AntiMagic psyk-resistant]] material around normal humans.
* ExtraEyes: Navigators possess a "Warp eye" allowing them to see the currents of the Immaterium and guide ships through it. This is not a poetic turn of phrase.
* FeudingFamilies: Among the Navis Nobilite, there exist conflicts known as Tradewars, which include limited conflict among the families. The Administratum tolerates these to a point, as long as they're short and not too destructive.
* GoMadFromTheRevelation: {{Averted|Trope}} by the Navigators when exposed to the Warp, which is what makes them unique in the setting in which this trope is otherwise played straight. Their ThirdEye allows them to perceive the Warp in a way which will not overwhelm their mortal mind, enabling their ability to guild a ship through its currents. This perception is subjective, and each Navigator will see it in a different manner, so that when they try to describe it to others, the only way they can do so is through vaguely poetic metaphor.
* ThePatriarch: The Paternova, the leader of the Navis Nobilite, who is called the "father of the Warp", and is somehow able to increase the Warp sense of his family's Navigators.
* WalkingTheEarth: Some Navigator families abandon their wealthy estates and take to wandering the galaxy.
* WeirdnessCoupon: The Navigators are mutants whose elders begin mutating beyond the norms of the "holy human form", and yet are fantastically wealthy and have a permanent seat on the High Lords of Terra. They're so absolutely vital to star travel that they have to be given these things.

[[caption-width-right:250:Top: An Ogryn.\\
Bottom: A Bullgryn BONE'ead.]]

->''- Listen, Ordrogg, the Emperor's very pleased with all of you, OK?''\\
''- Him? He's pleased?''\\
''- Very pleased. He's watching you now. He says he wants you to go over to the Robots and stick with them. You got that?''\\
''- Yerr. On our way.''

Ogryns are an abhuman strain, the product of high-gravity worlds with barren environments. They are large, even bigger than Space Marines, but are known for being very dumb. They are commonly used in the Imperial Guard as shock troops.

* {{Adorkable}}: Despite their poor hygiene, Ogryns are generally seen as lovable goofballs by the fanbase.
* ArtisticLicenseBiology: The Ogryns supposedly came about as a natural evolution of humans living on high gravity planets, with their increased muscle mass being used to offset the effects of gravity. In reality, this is likely the opposite of what would happen. Thanks to the SquareCubeLaw, high gravity worlds would favour smaller lifeforms, not larger ones (the Squats actually got this part correct).
* BashBrothers: When not organized into a unit unto themselves, an Ogryn will usually be paired up with a "little'un" whose job it is to stay with the Ogryn at all times and keep them pointed at the enemy during combat and make sure they do not accidentally [[TheKlutz hurt themselves]] [[AndCallHimGeorge or others]] while out of it.
* {{BFG}}: Ogryns will sometimes be employed as heavy-weapon teams, as they can easily swing around a large gun that would otherwise take two soldiers and a carriage to wheel around. Said Ogryns typically do best with weapons that have [[MoreDakka a high rate of fire]] and require [[BottomlessMagazines little or very simple reloading]] since it is easier to hold an Ogryn's interest with such a "toy" that they continue to use it to enthusiastic effect.
* CanisLatinicus: The official Ogyrn species name is ''Homo sapiens gigantus''. However, there are seven distinct types, including ''H. s. gigantus gigantus'' and ''H. s. gigantus cranopus''.
* {{Claustrophobia}}: Ogryns commonly suffer from extreme claustrophobia, with enclosed spaces making them very frightened and jumpy. In some editions of the rules, this claustrophobia was so bad that Ogryns were unable to enter a transport vehicle unless they were accompanied by a character as [[UndyingLoyalty no Ogryn would refuse a direct order]], no matter how uncomfortable it made them.
* DumbMuscle: Ogryns are massive, powerful, and dumb, even moreso than your basic Ork Boy. During the Literature/HorusHeresy, it was said that those who fought on the Chaos side only did so because were told the other guys had betrayed the Emperor. The smarter ones are given [[BioAugmentation augmetic upgrades]] called Biochemical Ogryn Neural Enhancement ([[FunWithAcronyms BONE]]) to boost their intelligence a bit more. This allows them to become sergeants of Ogryn squads, called ''Bone'eads''.
* EvilCounterpart:
** Chaos forces also makes use of Ogryns. Ogryn Berserkers are Khornate warriors, lobotomized and driven to murderous fury by a drug called Slaught. Plague Ogryns are used by the armies of Nurgle as walking disease incubators due to their size, strength, and endurance.
** In general, "Big Mutants" tend to be depicted as being akin to Ogryns or as corrupted Ogryns.
* HumanShield: The 2014 Astra Militarum codex introduced Ogryn specialists known as Bullgryns whose functionality in the armor is to act this way. Turns out that an Ogryn inside a massive suit of carapace armor and carrying a huge tower shield or force-field projecting buckler is a pretty good mobile wall. When you arm him with an underarm-slung grenade launcher, which is reinforced so it can stand up to being used as an improvised tonfa, or else with an armor-vaporizing greatclub, he can dish out a fair amount of damage, too.
* ImprovisedArmor: The front plates of Bullgryn carapace armor are made from sections of tracks from Leman Russ tanks.
* ImprobablyLowIQ: To give you an idea of how dumb Ogryns are, Nork Deddog, the setting's most famous Ogryn, knows the first letter of his name ("N is for Nork!") and can count to four. These accomplishments are said to make him a genius of almost unparalleled intelligence for an Ogryn.
* TheKlutz: Their great strength and poor self-control means that they tend to accidentally break things that they interact with, unless those things are large and reinforced. Hence why they virtually always use customized equipment.
* OurOgresAreDifferent: Ogryns are Abhumans who evolved on high-gravity worlds with barren environments. Unlike the Squats, who developed in roughly the same kind of environment but are much like classic dwarfs, Ogryns are huge, standing taller than even Space Marines.
* ThePigPen: Ogryns are known for being flabby and having horrible hygiene, and are often called Fats, Flabs, Slobs and Stenches as a result.
* PistolWhipping: In battle Ogryns will often use whatever they have at hand to batter their foes into a bloody pulp. As such the standard armament used by Ogryns, the ripper gun, is designed to be as sturdy as possible so that its wielder can be repeatedly used as a club yet still fire afterwards. The 8th Edition of the game gives the ripper gun both a ranged and melee stat line to represent this.
* PsychopathicManchild: Played with. Ogryn are taught to hate and kill the enemies of the Imperium, but this is usually the result of exploitation of their innocent, childlike nature more than inborn aggression.
* ShotgunsAreJustBetter: The Ripper gun is the Ogryns' standard firearm, and is used just as much as a club as a shotgun.
* UndyingLoyalty: Ogryns believe that the Emperor has personally issued them every order (being worked down from the chain of command) and thus obey orders to the best of their abilities. In a tragic demonstration of this, many Ogyrns fought on the side of Chaos during the Horus Heresy, but they didn't ''knowingly'' do so: they all genuinely believed that they were still fighting for the Emperor and the Imperium, when really it was their superiors misleading them with lies.
* UpgradeArtifact: Ogryn Bone'eads are Ogryns who have received extensive brain augmentation by the implantation of very high-quality neural implants provided by the Adeptus Mechanicus. Such implants are rare and precious, and few outside of the Cult Mechanicus are ever blessed with them, but in the case of Ogryns the Munitorium considers it worth the expense and effort to get at least one Ogryn in every group enhanced in this manner, as having a squad leader who can fully understand orders and think independently (if not particularly creatively) is a great force multiplier for Ogryn squads.
* WeirdnessCoupon: They're mutants, but they make extremely loyal soldiers who love cracking heretic and xeno skulls for the Emperor.


->''Little thieves! Thieves and vagabonds, the lot of them. They're petty-minded, larcenous little subhuman scum to the last. Everyone overlooks it because they can shoot straight and can cook a decent meal. You can't trust them... any of them. They'll steal your chrono if you shake hands with them, and as likely to pick your pocket as praise the Emperor's name...''
-->-- Anonymous Imperial Guardsman

Like Ogryns, Ratlings are an abhuman strain commonly used in the Imperial Guard. However, they are the polar opposite of Ogryns in nature and function. Of very short stature, Ratlings are used as snipers and stealthy infiltrators, and also as cooks, roles at which they excel. However, they can be a disruptive presence as well, as they're known to be hedonistic and have a streak of kleptomania.

* CanisLatinicus: The official Ratling species name is ''Homo sapiens minimus''.
* DyingRace: Ratling populations have suffered greatly due to Tyranid invasions of their worlds.
* ExplosiveBreeder: Ratlings procreate like there is no tomorrow... [[EverythingTryingToKillYou and there may not be]].
* FantasticSlurs: Due to their short stature, Ratlings are also referred to as Runtlings, Stunties, Halflings, or Maggots.
* FriendlySniper: {{ZigZagg|ingTrope}}ed. Ratlings are gregarious, enjoy a good feast, and make excellent snipers, but ''The Imperial Infantryman's Uplifting Primer'' warns that petty crime rates and illegal gambling increase in regiments with Ratling squads attached.
* TheHedonist: Ratlings enjoy the finer aspects of life, which means they love to eat until sick, drink like fish and breed like rabbits.
* {{Hobbits}}: Like Tolkien's hobbits, Ratlings are very short, compactly built, and tend to be portrayed with large, hirsute feet. They also love food, both the making and the eating.
* LongRangeFighter: These snipers are one of the worst units for close combat, so keep anything that could charge them very far away or see them beaten to death.
* MedievalStasis: Ratling worlds are largely agricultural and medieval in culture and civilization, with the Ratlings' unambitious nature and culture of hedonism keeping them that way.
* SniperRifle: Ratlings are often recruited into the Imperial Guard as snipers, equipped with sniper rifles and flak armour.
* SupremeChef: Not exactly, but they can certainly do a lot with very little.


->''We have always been a race of traders. It is natural to us that we should trade the fighting skills of our Brotherhoods. As well as bringing us a profit, it also allows our youngsters to gain experience and honour, and to keep alive the skills which our strongholds may one day need for their own defence.''

One particular abhuman faction that has caused some controversy is the Squats, a race of abhumans that adapted to subterranean life on high-gravity worlds near the galactic core. Separated from mainline humanity for tens of millennia, they grew shorter and, well, squatter, eventually coming to resemble the traditional fantasy dwarf in both appearance and temperament. Due to the difficulty of living on barren planets with radioactive surface conditions, the Squats developed extremely reliable food production systems, armor, and other technology, but also had a fatalistic attitude toward life. Over time, they made contact with the Orks and Eldar and gained a reputation for their high-quality tech, shrewd business dealings, and potent military defense. Eventually they were rediscovered by and reabsorbed into the Imperium, as their tech fascinated the Adeptus Mechanicus and made them a welcome addition to the Imperial armed forces, but they maintain a high degree of autonomy.

As a game faction, the Squats were never popular, nor did they fit very well in the increasingly GrimDark setting. They were included back in the days when ''[=40K=]'' was a transparent [[AC:[[RecycledInSpace In Space]]]] version of ''TabletopGame/{{Warhammer}}'' and every race in the latter had to appear in the former, but as the setting matured the Squats felt more and more out of place. Game designers never really decided on a "tone" for the army, and depictions of them wavered between goofy space dwarfs and miniature biker dudes. In 1994, they were discontinued with the explanation that the newly arrived Tyranids had descended upon their Homeworlds and stripped them clean of all life (like they do). A handful of embittered Squats still survive spread across the vast Imperium, but as a faction they are absolutely, positively never coming back. In fact, it was once Games Workshop's official position that they won't even be ''mentioned'', although this policy has relaxed enough that the reprinted edition of ''Space Marine'' lists an encounter with Squats in the novel summary, and every rulebook since 6th Edition has mentioned the Squats as being one of the main strains of abhuman. In 2018, the Squats finally made a return to the tabletop with a new model in the form of Grendl Grendlsen, a Hired Gun for the 3rd Edition of the GaidenGame ''TabletopGame/{{Necromunda}}''.

* BadassBiker: Well, ''triker''. This was one of the very few unique, consistent parts of the Squats' racial identity.
* BaseOnWheels: The Squat's Land Trains, which are several of these linked together to form a larger mobile structure. Usually each car would have its own specialization, such as artillery platforms or flyer landing and service pads.
* CanisLatinicus: The official Squat species name is ''Homo sapiens rotundus''.
* TheBusCameBack: February 2018 saw the announcement that a new Squat mode, the first in 20 years, would be produced for the GaidenGame ''TabletopGame/{{Necromunda}}''.
* CanonDiscontinuity: Between the 3rd and 6th editions of ''Warhammer 40,000'' Creator/GamesWorkshop refused to acknowledge the Squats as part of the setting, taking measures ranging from simply ignoring any questions about them to suspending posters being from the official Games Workshop forums for mentioning them too much. Some Black Library novels were even rewritten slightly when they were rereleased, such as Grimm from Ian Watson's ''Inquisition War'' trilogy being RetConned into a Tech Priest.
* ChuckCunninghamSyndrome: It took Games Workshop a while to decide if they wanted to keep the Squats in the setting or not, which meant that there was a long period of time where there was really no word on when the next update for them was coming out until they finally made their dropping official.
* CoolAirship: The Squats were known to field heavily-armored, rigid-bodied lighter-than-air craft in battle.
* DemotedToExtra: The current status of the Squats is as a background only strain of abhumans, briefly mentioned in the 6th and 7th Edition rulebooks. They no longer have any models or army lists of their own on the tabletop.
* DroppedABridgeOnHim: When they were first discontinued the reason stated in the background information was that the Squat Homeworlds had been devoured by a Tyranid Hive Fleet. This idea was [[RetCon subsequently dropped]] from canon.
* ElvesVersusDwarves: {{Downplayed|Trope}}. The Squats used to trade with the Eldar during their Age of Isolation before the establishment of the Imperium. But when they were attacked by Orks, they sent requests to the Eldar for aid, which the Eldar ignored. Relations between the Squats and the Eldar have been cold ever since then, with the Squats regarding the Eldar as unreliable and untrustworthy.
* {{Expy}}: As with many other factions who date back to the 1st Edition of ''Warhammer 40,000'', the Squats were originally created as a far future version of their ''TabletopGame/{{Warhammer}}'' counterpart, the Dwarfs.
* FutureCopter: The Iron Eagle Attack Gyrocopter is the primary aircraft used by the Squat Engineers Guild. The Iron Eagle has a high-powered turbofan mounted on each side of its hull which, when combined with the aircraft's gravitic thrusters, gives it phenomenal manoeuvrability.
* HeavyWorlder: Strangely enough, the Imperial Guard's [[TheOgre Ogryns]] also come from high-gravity worlds, but turned out completely different. The demands of their unbreathable high-pressure atmospheres and underground warrens may have been a contributing factor to the Squats current size.
* HigherTechSpecies: The Squats were very dependent on their technology from the foundings of their Homeworlds, and lost only a small fraction of it in comparison to what the bulk of the humanity lost from the Dark Age of Technology. Spared from the restrictions of the Adeptus Mechanicus, the Squats innovated freely, their harsh situations making such necessary. When the Imperium finally reestablished contact with them, the Squats had developed a wide variety of technologies that no one else had, such as power generators which drew directly from the Warp, and neo-plasma, as well as superior metallurgy.
* MoodDissonance: Part of the reason Squats were problematic were that they tonally did not fit in with the rest of the setting.
%%* OurDwarvesAreAllTheSame: Even in space!
* PoweredArmor: The elite Hearthguard wear suits of Exo-armour, heavy armour comparable to suits of Imperial Terminator Armour.
* PrivateMilitaryContractors: Squat mercenaries are highly sought after renowned for their skill, determination and reliability, especially when fighting against Orks. Early editions of the ''Epic'' scale version of the game represented this by allowing any army, except Orks and Chaos, to include companies of Squad mercenaries in their force.
%%* ProudWarriorRaceGuy: Because Dwarfs are.
* RecycledInSpace: The Squats were 40K's take on the Dwarfs from ''TabletopGame/{{Warhammer}}''.
* TheScottishTrope: An unofficial but heavily enforced rule on the old Games Workshop forums was that anyone who stated that the Squats should be brought back would be banned. Therefore, any mention of them would decidedly have to avoid a direct reference to their faction's name.
* TargetSpotter: Colossus super-heavy vehicles are always accompanied by an Iron Eagle Gyrocopter that maintains a constant data-link with the massive war machine's fire control centres so that it can instantly relay accurate targeting data. In game terms this partnership allows the Colossus to use the Gyrocopter's line of sight when firing its artillery weaponry.
* TunnelKing: As a culture. The Squat Homeworlds almost never had a breathable atmosphere, and often a high pressure one at that, so the Squats became experts in underground construction and living by necessity. This in turn is part of why they were so hard to rout when invaded--their underground warrens were resistant to bombardment from above and the confined spaces would heavily favor the defenders.
* WarForFunAndProfit: Best summed up by this quote:
-->You people do well at war because you treat it as a religion. [[WarForFunAndProfit We do well because we treat it as a business.]] It is just a matter of outlook.
* WaveMotionGun: The monstrous Hellfury Cannon mounted on the Cyclops super-heavy vehicle fires a stream of phased particles that react with each other to create a beam of pure energy that can destroy any target it hits. Even [[DeflectorShields energy fields]] are little protection as the energy flux within the beam overloads them in swift succession.
* WeirdnessCoupon: The Squats were only ever part of the Imperium in the most nominal sense, the Great Crusade having fought almost to a stalemate over their worlds when the Imperium tried to forcibly absorb them. The conflict was settled with a variety of treaties in which the Squats could maintain their self-governance without Administratum oversight and were allowed to maintain their own culture, only offering the Imperium their occasional effectual support. The fact that they maintain their own culture, do not report to Imperial authorities, vary from the norm of the Holy Human Form, and do not believe in the Imperial Cult would normally be seen as an unacceptable level of deviance on the Squats' part. However, this arrangement works due to the general stability of their genome, their fundamental reliability, dislike of xenoforms, and resource and technology contributions to the Imperium.

[[folder:Officio Assassinorum]]
[[caption-width-right:350:L-R, top to bottom: Eversor, Vindicare, Callidus, and Culexus assassins]]

->''For those that defy the Imperium, only the Emperor can judge your crimes. Only in death can your receive the Emperor's judgement.''

The Officio Assassinorum (Office of Assassins) is one of the Imperium's most closely guarded secrets. Consisting of a series of Temples on Terra, each one dedicated to creating and training its members in a particular style of wetwork, the Assassins work in stealth and subterfuge, slaying enemy targets and (it's rumored) Imperial targets who have exceeded their bounds. The Grand Master of the Assassins is one of the High Lords of Terra.

There are many Temples of the Assassins in the service of the Imperium, the largest and most famous of which are:

* '''Callidus:''' Specializing in infiltration, subterfuge, and impersonation
* '''Culexus:''' Dedicated to eliminating psykers
* '''Eversor:''' Berserkers used for shock and awe assaults
* '''Vindicare:''' Peerless snipers and sharpshooters.

Other Temples include:

* '''Vanus:''' Data gatherers and manipulators ''par excellence'', skilled in using other people to make their kills
* '''Venenum:''' Master Poisoners

Of these temples, the Callidus, Culexus, Eversor, and Vindicare are represented with models for the game.

Originally classed as "diplomatic agents" in the 1st Edition of ''Warhammer 40,000''[[note]]also known as Rogue Trader[[/note]], the Imperial Assassins were revamped into their current form during 2nd Edition and have had rules in most subsequent editions. ''TabletopGame/AssassinorumExecutionForce'', a [[GaidenGame board game]] pitting all four major assassin types against Chaos Space Marines, was released in 2015. The 8th Edition rules for assassins are included as part of the ''Index: Imperium 2'' book released in June 2017.

* AbnormalAmmo: In the background material, and some editions of the rules, Vindicare Assassins are equipped with a variety of specialized shells used in their Exitus weapons. Expensive and very rare, these shells are capable of [[ArmorPiercingAttack one-shotting a tank]], nullifying DeflectorShields, or injecting the target with a [[UniversalPoison lethal neuro-toxin]].
* AbsurdlySharpBlade: The Phase Swords used by Callidus Assassins are able to cut through absolutely anything by phasing in and out of realspace.
* AntiMagic: The specialty of the Culexus. In addition to them being able to mess with psykers just by being near them (due to being Blanks), the Animus Speculum weapon mounted on their helms draws power from nearby psykers to shoot bolts of anti-psychic energy that are especially lethal to psykers. In-game, they have a number of special rules that make them particularly adept at targeting psykers, such as the Abomination rule that gives the psyker penalties to their Psychic and Deny the Witch tests.
* AmazonBrigade: The vast majority of Callidus assassins are female, as Polymorphine works better for women.
* BadGuysDoTheDirtyWork: The Assassins were founded so that the Emperor would never have to get his hands dirty. They also have vaults containing forbidden alien technology which the Adeptus Mechanicus would consider heretical.
* TheBerserker: Eversors, who are [[ExplosiveOverclocking pumped so full of performance-enhancing combat drugs that their bodies explode if the drug flow stops]]. Because [[PsychoSerum these drugs enhance lethal aggression]] and cannot be shut off without killing the addicted assassin, [[SealedBadassInACan putting them into cryo-stasis]] is necessary to keep them alive between deployments.
* {{BFG}}: The [[SniperRifle Exitus Rifle]], wielded by the Vindicare assassins.
* BladeBelowTheShoulder: Phase swords are worn on a on a bracer attached to the back of a Callidus assassin's wrist so that she has her hand free to manipulate objects and wield her poisoned blades.
* BrainComputerInterface: Vanus assassins are equipped with specialized augmetics that increase their brains' ability to absorb data, essentially turning them into human computers.
* BrainwashedAndCrazy: Some of the more... "[[AxCrazy volatile]]" Imperial assassins are subject to this, being mindwiped after every mission and having their next mission subliminally programmed into them while kept sedated. Eversors are a common example, though this is not necessarily limited to them.
* CharlesAtlasSuperPower: While there is some element of augmentation common to many assassin temples, much of an assassin's abilities come from their long TrainingFromHell as much as anything else.
* TheChessmaster: The Vanus Temple consists entirely of these. As one of their members said, 'the cleanest kill is one that another performs in your stead with no knowledge of your incitement'.
* CoolHelmet: Culexus assassins have virtually all their equipment mounted in their helmet. Said helmet is necessarily so over-sized to accommodate this that one speculates they get neck-reinforcing augmentations to wield it effectively.
* EyeBeams: Culexus assassins' primary weaponry are built into their skull-shaped helmets, with point of discharge being mounted over the eyes. [[DeadlyGaze Their looks can literally kill.]]
* HandCannon: As if they weren't overcompensating enough with their [[{{BFG}} Exitus]] [[SniperRifle Rifles]], the Vindicare assassins also get the Exitus ''Pistol'', which is supposed to provide them with [[MoreDakka plenty of firepower]] in the [[EmergencyWeapon event of an emergency]].
* ImprobableAimingSkills: Assassins of the Vindicare temple are expert marksmen and infiltrators, complete with special guns and ammunition allowing them to potentially one-shot a tank from kilometers away. In-game the Vindicare's ''Deadshot'' Ability makes them one of the few units capable of targeting a character model, even if they aren't the closest model.
* IWorkAlone: Assassins are deployed at maximum number of four and they never work with anyone else.
* KillAndReplace: Callidus Assassins not only kill their targets, they frequently assume their roles and duties in order to cause subtle disruptions and destabilize the entire operation.
* MasterPoisoner: While many assassins utilise a variety of poisons and toxins on their missions, operatives of the Venenum Temple are the true masters of the art. One piece of FlavorText details the successful assassination of all thousand members of an anti-Imperial planetary government by the Venenum Assassin Urua Thereaux who spent three days poisoning the chairs of their council chamber.
* MixAndMatchWeapon: The executioner pistols wielded by members of the Eversor Temple are specialist combi-weapons consisting of a bolt pistol and a needle pistol. These weapons are able to unleash a hail of mass-reactive bolts before quickly switching to firing [[PoisonedWeapons highly toxic darts]] that can kill with the merest scratch.
* MurderInc: The Officio Assassinorum provides elite assassins used by Imperial organizations such as the Inquisition. The Grand Master of Assassins, the head of the Office, is one of the High Lords of Terra, and is heavily monitored by the other High Lords, as the Grand Master could (and at one point did) easily wipe the others out.
* OurFounder: The Assassin Temples are named after the people who built them.
* OurSoulsAreDifferent: Culexus assassins are horrifying creatures that seem to lack a soul, thanks to the Pariah gene. Ordinary people find them [[BrownNote quite disturbing]], but the assassins are trained to [[MageKiller prey on enemy psykers]], who are especially sensitive to them. Their wargear fires what has been described as bolts of [[AntiMagic anti-soul]].
* PoisonedWeapons: Callidus assassins carry multiple poisoned knives and needles about their person as secondary weapons. The assassin will use these blades against particularly tough opponents as their poison is so lethal they will wound any living opponent.
* PsychoPrototype: Legienstrasse, the lone assassin created by the now-defunct Maerorus Temple, went rogue and took an ''insane'' amount of effort to kill, including multiple attempts by the Space Marines, Inquisition, and other Assassin temples.
* RuleOfSeven: There are seven Assassin Temples.
* ShapeShifter: Callidus assassins have access to Polymorphine, allowing them to disguise themselves as a member of just about any race. They are employed to infiltrate enemy organizations, supply them with false intelligence or bad advice, and surgically remove the leadership.
* SkullForAHead: An Eversor's helmet resembles a glaring skull. The old model of the Culexus also featured a skull-like face, but the new model's face is more like a mask with a huge leering grin.
* SpyCatsuit: The stereotypical garb of an Imperial Assassin is a layer of "synskin", a kind of semi-organic body sheath applied directly over the assassin's flesh. Multiple variations of it exist, some of which enhance strength, others of which have chameleon qualities, and some are capable of changing shape (along with the wearer).
* StraightForTheCommander: During the 32nd millennium, Drakan Vangorich (then-Grand Master of the Assassins) orchestrated the deaths of all the other High Lords in a bid to take control of the Imperium. He was eventually killed by a Space Marine strike force, but not before an extremely bloody conflict.
* SuperReflexes: Imperial Assassins of all stripes have their reflexes trained to such a level that they can literally DodgeTheBullet in combat.
* SwallowedWhole: One piece of FlavorText tells the tale of an infamous Callidus assassin known as Mother Gullet. Upon discovering that her target, a defiant Imperial Governor, had a young son that he doted on, the assassin infiltrated the palace and used [[VoluntaryShapeshifting the shapeshifting drug]] [[TransformationTrinket Polymorphine]] to distend her jaw so that she could swallow the infant prince and smuggle him out of the palace inside her own body. The Imperial authorities were then able to use the prince as a hostage to ensure the Governor's compliance.
* TakingYouWithMe: The Eversor assassins, in addition to their [[ExplosiveOverclocking dangerously unstable cocktail]] of [[PsychoSerum chemical enhancements]], also have two-part explosive chemicals in their body. As long as their heart keeps circulating blood, the two parts will not come into contact, but once the Eversor is killed the blood stops circulating and the chemicals join, causing the assassin to explode and ensure that their target is killed even if the Eversor only survives long enough to get near the target.
* TrainingFromHell: All Assassin candidates are selected as children and go through 10 years of harsh, intensive training just to become novice assassins, with tests and trials continuing throughout their lives.
* TransformationTrinket: Callidus assassins use a drug known as Polymorphine to achieve their VoluntaryShapeshifting. When properly trained, Polymorphine allows the operative to alter her body to assume the appearance of [[{{Humanshifting}} any human and most humanoid aliens]]. Transformation into more monstrous xenos and mutants is possible by combining Polymorphine with biogenetically created implants surgically inserted into the assassin's body that react with the drug to create specific forms.
* WhoWatchesTheWatchmen:
** The Inquisition's Ordo Sicarius monitors the Assassins to keep another major power grab from ever happening.
** Certain elements of the Inquisition have secretly sought ways to police or even eliminate the Space Marines, and the Assassins are privy to these machinations.
* WolverineClaws: The primary close combat weapon of the Eversor Assassin, the neuro-gauntlet, consists of an armoured glove with hyper-alloy blades and syringes built into its figures that inject [[PoisonedWeapon lethal neuro-toxins]] into the target.

[[folder:Sisters of Silence]]

The Sisters of Silence are arguably the best weapons against psykers that the Imperium has to offer, a mysterious group of heavily armed women who are also Blanks, whose mere presence can shut down some of the mightiest agents of Chaos. Organized by the Emperor himself, they have been part of some of the greatest battles in history, such as the Sacking of Prospero, the Siege of Terra and the Great Crusade. After the Horus Heresy, they all started to disappear, with many different reasons being given, such as disgust with the current state of the Imperium, only to slowly reform after the War of The Beast and make their full return aiding Guilliman against Magnus the Red.

Like the Adeptus Custodes, the Sisters of Silence first received rules and models in the ''Horus Heresy: Burning of Prospero'' [[GaidenGame board game]] and in March 2017, they received an official mini codex in the 7th Edition ''Talons of the Emperor'' box set. The rules for the Sisters of Silence in 8th Edition are included in the ''Index: Imperium 2'' book that was released in June 2017.

* AmazonBrigade: The Imperium's first all-female fighting force, millennia before the Adepta Sororitas.
* AntiMagic: Like the Culexus Assassins, every Sister of Silence is a Blank, having no Warp presence. This makes psykers acutely uncomfortable in a Sister's presence, even causing actual pain, and their psychic abilities are dampened or even shut down.
* {{BFS}}: [[CloseRangeCombatant Vigilator Sisters]] are armed with executioner greatblades, two-handed swords as long as the Sister wielding them is tall, that are capable of cleaving through flesh and armour with equal ease.
* BlingOfWar: As with the Custodes, they are clad in gilded Vratine armor.
* HeroWorshipper: The Sisters revere Roboute Guilliman as a living saint. However, they are also one of the few groups in the Imperium who don't worship the Emperor as a god (until now), though they are fanatically loyal to him otherwise.
* MageKiller: It is the role of the Sisters of Silence to hunt down and eliminate the greatest psychic threats that the Imperium faces. The Null-Maidens of the Silent Sisterhood are highly trained in the elimination of those who use PsychicPowers and are equipped with special anti-psyker weaponry. The 8th Edition rules represent this specialisation by giving every Sister of Silence psyk-out grenades (which have a chance of dealing [[UnblockableAttack mortal wounds]] against psykers and Daemons) and the Witch Hunters special rule (allowing them to re-roll wound rolls against psykers they are fighting). The rank and file [[LongRangeFighter Prosecutor Sisters]] are also able to ignore the usual targeting restrictions when firing at psychic characters.
* TheSpeechless: The Sisters' name is literal, as they take a vow of silence called the Oath of Tranquility upon promotion to full Sisterhood; initiates can talk freely. This is reflected in their armor covering their faces below the eyes. They communicate mainly in their own type of sign language called Thoughtmark, but are skilled in others, including the battlefield signage used by the Astartes.