User blog:Sclera1/Monsters in Doom 3

List of monsters in Doom 3

Imp
In Doom 3, the Imp still appears human, but the face was changed from having red eyes to having 10 small dark eyes. The shoulder spikes were removed, giving it more of a straightforward-monster appearance than a traditional demon. Unlike the previous Imps, these are capable of leaping great distances and moving at great speeds to attack. They also emit a loud chimp-like screech and can crawl on walls and other surfaces. They retain their fireball attack. Two other demons, the Maggot and Wraith, appear very similar to it and could possibly be related to it.

In the Hell level of Doom 3, the Imps have orange skin and have a rocky frame.

If you observe a lot in the expansion pack Doom 3: Resurrection of Evil, you can see a Hell Knight pick an Imp up, bite a chunk out of it and toss it away. It seems that the Imp might be preyed on by the much larger demon.