Imp/Doom 64

The Imps are featured in DOOM 64, first appearing in MAP01: Staging Area.

Background
The Imps of DOOM 64 are resurrected carcasses of those from DOOM, resurrected by the Mother Demon. They are made from systematically altered dead carnage remade back into corrupted living tissue. The mutations were devastating. The Demons have returned stronger and more vicious than before.

The manual for DOOM 64 describes the imp with this passage:

''You thought an imp was a cute little dude in a red suit with a pitchfork. Think again. This Imp heaves balls of fire down your throat and takes several bullets to die. It's time to find a better weapon than a pistol, if you're going to face more than one of these mutants.''

With further mutations they now have a sleeker appearance, only having noticeable spikes along its back. These Imps do not appear to have mouths like their classic counterparts (looking a bit like Sawcubi) -- although they do give out cries when shot, which would presumably require them to have mouths. The back of their heads comes to a point.

A more powerful variant with further mutations is known as the Nightmare Imp is also one of the new monsters in the game.

These versions of the Imps also feature discrete animations for melee attacks versus ranged attacks, similar to the Revenants in other games. This means that unlike other versions of the game, the Imps will not throw a hell-fire ball if their melee attacks miss the player (since in other versions, the attack type - hell-fire ball or melee - is determined by the victim's proximity at the end of the attack animation).