Imperium
The Imperium of Man is a galaxy-spanning interstellar Human empire, the ultimate authority for the majority of the Human species in the Milky Way Galaxy in the 41st Millennium A.D. It is ruled by the living god who is known as the Emperor of Mankind.
The founder and ruler of the Imperium is the god-like Emperor of Mankind, the most powerful Human psyker ever born. The Emperor founded the Imperium over 10,000 Terran years ago in the late 30th Millennium during the Unification Wars on Old Earth following the terrible period in Human history known as the Age of Strife.