In the late 41st Millennium, Abhumans are those descendants of baseline human settlers who have mutated and evolved after being isolated on worlds across the galaxy with various extreme environmental conditions. The term may be short for "aberrant human", "abnormal human", or, less pejoratively, derived from the Latin term ab humanis, "from humans". In an Imperium of Man where genetic mutation and spiritual corruption are often viewed as interrelated, Abhumans are a focus of much controversy for the Imperial government. In more liberal times under the direct rule of the Emperor of Mankind during the Great Crusade, even markedly divergent Abhumans such as the Beastmen could serve in the Imperial Guard. Since the Emperor's stasis in the Golden Throne began, however, only the lesser Abhuman mutants, such as Ogryns and Ratlings, are allowed full citizenship in the Imperium. However, they are still distrusted by the Puritan members of the Inquisition.
(Homo sapiens variatus) are horned, hoofed, and quite hairy Abhumans. They were formerly recruited for the Imperial Guard, where they used their bloodlust to fight for the Emperor and atone for the sin of being born as mutants. They were led by other Beastmen called Packmasters. In recent times "Pureblood" Beastmen are no longer seen in Imperial service, Beastmen now only serve in the Forces of Chaos. No doubt Puritan elements of the Inquisition convinced the Administratum that the Beastmen could not be so radically altered from the normal human form without being tainted by Chaos. Some lesser variants of the H.s.variatus strain, who are less physically mutated than their peers, are allowed to still exist within the Imperial armed forces, where they are still used for cannon fodder and as expendable assault troops.
- Main article: Ogryn
The dim-witted human subspecies called Ogryns (Homo sapiens gigantus) evolved on high-gravity, low-temperature prison planets. They are huge and stupid, but unquestionably loyal once introduced to the Imperial Cult. Ogryns are used as the Imperial Guard's shock troops, and for this role, they are commonly outfitted with the Ripper Gun. The Ripper Gun is a weapon simple enough for them to operate, although some feral Ogryn cannot even fathom this device. Ogryn are also frequently used as bodyguards by Imperial Commanders. Ogryns tend to be claustrophobic and thus are difficult to transport. They are typically led by "Bone 'eads," who have undergone a procedure known as Biochemical Ogryn Neural Enhancement (or BONE treatment), improving their intellect to near-human standards. Sometimes, when speed is of the essence, Imperial commanders with a fresh batch of conscripted Ogryns don't bother to teach them the comparatively complicated use of the standard Ogryn Ripper Gun, merely giving them another club and telling them to smash up the enemy.
Ratlings (Homo sapiens minimus) are small, loud, hungry and lecherous Abhumans who often serve as snipers in the Imperial Guard, a role at which they excel. Ratlings also serve as cooks for Imperial Guard Regiments, a skill they no doubt learned in order to feed their own seemingly bottomless stomachs; and they also have kleptomaniac tendencies, as Commissars report petty theft and illegal gambling rings increase substantially when Ratlings are attached to a platoon, company or regiment. One named Ratling world is Ornsworld, which was attacked by Abaddon the Despoiler during the The Gothic War. Ratlings are a mutant sub-branch of the human race, like the Ogryns, who adapted to living in underground tunnel systems on worlds with hostile surface environments. Due to their size, they often bear the brunt of human soldiers' jokes, although more than one soldier has been saved by the Ratlings' superior marksmanship.
The Abhumans called Squats (Homo sapiens rotundus) originated on high-gravity mining worlds close to the galactic core, making them short, muscular and tough. Their homeworlds briefly seceded from the Imperium during the Age of Apostasy, though they later returned to the Imperial fold as autonomous but loyal worlds. Squats are talented engineers, and known to hold long-standing grudges, particularly against the Orks. In combat, Squats use combat motorcycles and support from superheavy artillery weapons, such as Leviathans and Colossi.