- "While vile mutants still draw breath, there can be no peace. While obscene heretics' hearts still beat, there can be no respite. While faithless traitors still live, there can be no forgiveness."
Mutants are the millions of people across the Imperium of Man who have been deformed from the baseline human phenotypic state by genetic mutation. This mutation can be caused by environmental factors or by exposure to the raw psychic power of Chaos. These people are destined to become the outcasts and lower classes of Imperial society. They are shunned and are often hunted down and killed as the Imperium has little tolerance for any who deviate from the perfection of the baseline human form in mind or body. Mutation is actually considered a heretical crime against the Emperor of Mankind by Imperial authorities because of its connection to sympathy or worship of Chaos. Human mutants are often terribly misshapen creatures, abominably deviating from the normal human form. On the other hand, not all mutants are degenerate beasts; many only bear a few extraordinary traits setting them apart from the rest of Mankind. While many mutants are born mutated as a result of their ancestors' exposure to mutagens like radiation or extreme planetary environments over many generations, exposure to the psychic energies of Chaos can also lead to rampant mutation. Because those who secretly worship the Chaos Gods as Chaos Cultists are known to be granted mutational "gifts" by their dark masters, physical mutation can be an indicator of inner spiritual corruption by Chaos. This is another reason that all mutants are considered suspect by the Imperium's authorities and are greeted as general social pariahs by almost everyone else across the human-settled galaxy. Navigators are also considered mutants, but were actually intentionally created through the use of genetic engineering in the distant past, probably during the Dark Age of Technology to make it possible for Mankind to use the Warp-Drive for interstellar travel. Because they are absolutely vital part to the Imperium 's commerce and defence, they, alongside Imperial Sanctioned Psykers and certain species of Abhumans, are the only officially-tolerated form of mutants.
Life in the Imperium for Mutants
On many Imperial planets, mutants are quickly abandoned by their parents and have to quickly learn how to take care of themselves. They are almost always the worst off people in imperial society. It is very rare to find a world that will tolerate them and not discriminate against them. These worlds are a paradise for mutants compared to most worlds of the Imperium. Desperately seeking some form of acceptance, many mutants join rebellious cults. Most of these cults simply condemn the faults of imperial society but others worship chaos and plan rebellion. These cults easily corrupt mutants due to the discrimination they have suffered. On most worlds mutants are not allowed to carry weapons for fear of rebellion. The weapons they do come to possess will often be primitive chains, knives, stubbers and slug-throwing revolvers.
Imperial Hatred of Mutants
The deep Imperial hatred for mutants and deviation from the standard physical human form is rooted in the earliest days of the Horus Heresy. During the Emperor's Great Crusade in the 31st Millennium to reunite the scattered colony worlds of humanity under the aegis of the Imperium, mutants were accepted and used as part of the Imperial Army, formed into their own squads or mixed with the ranks of the regular troops. However, after the Horus Heresy, mutants were outlawed by the High Lords of Terra for the part they had played in that terrible rebellion as the favoured servants of the Dark Gods. The post-Heresy association of most mutants with heretical and Chaotic cults has only cemented this hatred of them by the majority of the human population of the Imperium.
There are many types of mutations and some affect the mind rather than the physical body, producing individuals with the ability to access the psychic energy of the Immaterium and use it to reshape the physical world. These psychic individuals always run the risk of becoming a host for the malevolent entities dubbed daemons that inhabit the Warp. These mutants are generally referred to as psykers in Low Gothic and they are among the most feared of human mutants. Humanity is not a naturally psychic species like the Eldar or the Orks and the ratio of physical to mental mutation among humans is approximately 1000:1, or 1000 physically mutated individuals for every one born with psychic abilities. Psykers are not left to live out their existence like most mutants but are taken from their homeworlds by the Imperium in the Inquisition's Black Ships to be trained by the Adeptus Astra Telepathica since they are considered far too dangerous to be allowed to exercise their abilities without proper Imperial conditioning.The training of Sanctioned Psykers by the Imperium allows them to be used in battle, to fuel the power of the Astronomican by sacrificing their lives to help the Emperor maintain that great telepathic beacon of interstellar travel or to serve in the Choirs of Astropaths who telepathically communicate between distant worlds. They are tested for aptitude by the Adeptus Astra Telepathica and the dangerously unstable or those deemed too mentally weak to protect their minds from daemonic possession are executed immediately. The survivors are taken in the infamous Black Ships of the Adeptus Astra Telepathica to be transported to Terra for their training. Some will eventually serve in the roles mentioned above or are even assigned to the service of the Imperial Guard. The luckiest psykers may be adopted into the Chapters of the Space Marine where they become Librarians. Some may even eventually be accepted into the retinue of an Inquisitor as an Acolyte.
Psykers wield many and various powers, including the ability to gaze into the future, to shoot lightning out of their hands, to control the actions and minds of others and, most dangerously, to open portals from realspace into the Warp. The Warp is inhabited by many horrible and powerful entities such as daemons and the Enslavers. Psykers are like lights in a dark cave to these entities who can see them when they use their power and who desire an entry into the physical universe where they can unleash great mayhem among mortals. Therefore, whenever psykers use their powers they are at risk of possession by these Warp entities. A possessed psyker acts as a portal for daemons into the material world and may become a horrific daemonhost himself, spreading the corruption of Chaos wherever he goes. As more daemons come through the portal, they tear open the gateway further, slowly pulling a portion of the physical world into the Immaterium until reality begins to warp and reform under the strain of Chaos. Untrained psykers have no hope of survival against such an attack, and it was the occurrence of such tragedies when uncontrolled human psykers first began to appear at the end of the Dark Age of Technology that helped bring on the terrible destruction that consumed human space during the Age of Strife.
Other Races and Mutation
The powers of Chaos also produce mutation among the members of other species that are corrupted by it, but Mankind, with all of its psychic flaws and weaknesses, has always been particularly vulnerable to the temptations of Chaos and the mutations it brings. Among the allies of the Tau, the species known as the Kroot possesses the in-born ability to alter their own genomes and transform their physiology following the consumption of their enemies' bodies, gaining phenotypic traits that may add to their fitness as individuals and as a species.
- Black Crusade: Core Rulebook (RPG), pp. 20, 25, 50, 360
- Warhammer 40,000: Rogue Trader (1st Edition), pp. 52-57
- Warhammer 40,000 Rulebook (6th Edition), pp. 148, 158, 172-173, 177, 180, 218-219, 232, 404-405