The Imperium of Man is a galaxy-spanning interstellar human empire, the ultimate authority for the majority of the human race in the Milky Way Galaxy in the late 41st Millennium A.D. It is ruled by the living god who is known as the Emperor of Mankind.

However, there are other humanoid species classified as Imperial citizens, mainly mutant offshoots of genetic base-line humans who are known as Abhumans and include such human sub-races as the Ogryns, Ratlings and Squats.