For millennia, Mankind has been suffering increasing instability in its gene-pool. Thousands of years of exposure to radiation, carcinogens and the warp threaten to destroy the biological foundation of Mankind itself. During the shrouded times of the Age of Strife, this mutation was left to run unchecked and even hastened by internecine wars that employed all manner of horrifying atomic, chemical and biological weapons that further seared the genetic base of Humanity. Not only that, Mankind is slowly and tortuously evolving into a psychic race and mental powers are not the only manifestation of this painful evolution.
The position of Mutants within the Imperium varies from world to world. Mutation is almost universally regarded as a sign of spiritual deviation and a punishment from the Emperor for the sins of the parents. On the least technically-advanced worlds, where feudal rulers and barbarian hordes hold sway, superstition rules over any sense of common humanity and deformed babies are slain at birth. On the more advanced worlds, Mutants may be tolerated, but nowhere are they granted the few rights and privileges enjoyed by untainted folk. They are segregated and shunned, often formed into groups of slaves and forced labour, outlawed from inhabiting the same areas as normal citizens. Other persecutions may be heaped upon them, such as involuntary sterilisation, for Mutants are at far higher risk of giving birth to mutated children. However, not all mutations turn a man or woman into a sloughing-skinned, frothing beast, and many Mutants can pass a cursory examination. Where Mutants are tolerated, it is possible for such a hidden Mutant to rise to a position of authority, either socially or militarily. In fact, many of the Imperial Commanders and noble houses of the Imperium are rumoured to harbour Mutants within their ranks, and certainly it is the case that very powerful Mutants may retain their position even if their taint is discovered or widely rumoured.
Mutants are always viewed with disgust and suspicion, they are quite frequently made scapegoats for civil unrest, crimes and other anti-social behaviour. It is not surprising then that the Mutants' dissatisfaction can erupt into insurrection and rebellion. Such revolts are almost invariably bloody as the repressed Mutants violently throw off their chains and lash out at their erstwhile masters. Whole worlds, even star systems, have fallen to Mutant rebellions, but usually the Imperial response is swift and brutal, and such Mutant empires are short-lived.
As year on year the number of Mutants increases, they become an ever larger, and more downtrodden part of the Imperial populace. They form their own sizeable communities, have their own religions and customs, and have created their own societies within the labour camps and slave pens. Puritanical Inquisitors see such gatherings as potential dangers, treating all Mutants as heretics and malcontents simply by virtue of their birth. Many, some would say wiser, Inquisitors see Mutants as another resource at their disposal. As an underclass, they are all but invisible to most Imperial citizens - the slave in the kitchens, the worker in the fields, the laboratory assistant who is ever ready to help. Their eyes and ears see and hear everything, and a Mutant populace, if won over to a cause, can provide a mass of manpower if nothing else.
As an almost universal underclass, Mutants scavenge what they can, frequently dressed in little more than rags tied with twine and rope. They are mis-shapen creatures, twisted parodies of men and women, often showing hideous scars of their abnormal growth, as well as evidence of self-mutilation and punishment from their overseers. They crawl with vermin, finding solace in the other gutterfilth of rats, bats, beetles and flies, who they often share their living quarters with.
They are normally forbidden armaments, and those they possess are crude shotguns or blunderbusses, heavy duty revolvers, chains, whips and clubs which can be easily made and concealed. Many crave for a humanity which they will never possess, and cling onto whatever fragments of normal life they can, turning children's toys into talismans, and everyday tools and utensils into ju-jus and amulets.
Equipment: Almost all Mutants come from a despised underclass of Imperial citizenry, and will therefore be unlikely to have anything other than Common equipment.