The mancubus is a cyborg alien found in the DOOM Universe . The physical features of this creature consist of a stocky build, a large bloody mouth with sharp teeth, and twin rocket cannon appendages. It's skin is of a lighter brown complexion and does not contain any visible body hair. The Manucubus is rather slow moving due to its size but what it lacks in speed, it makes up for in the damaging effects of its projectiles.
The Mancubi (plural) came from a demonic dimension called Hell. When United Aerospace Corporation (UAC) scientists were experimenting with teleportation technology they accidentally opened a rift to this dimension. This caused a whole manner of demonic forces, including the Mancubi, to come through the portal onto Mars and the other bases. The demons brought destruction on the UAC bases and killed or possessed many UAC personnel. Not too much later, they made their way to Earth to continue their attack there. It was here that a single hero managed to close the rift between the dimension of Hell and the Earth itself.