Demon/Doom RPG

In both DOOM RPG and DOOM II RPG, the Demons appears as the "Pinky" class of monsters.

Background
There are three variations, identified by color:
 * Bull Demon (olive green)
 * Pinky (normal colors)
 * Belphagor (blue)

Pinkies will attack automatically the moment the player steps into an adjacent square, even if they have already moved that turn. They are resistant to rockets but susceptible to shotgun blasts.

Also in DOOM II RPG, in addition to a regular biting attack, each of the "Pinky" class monsters have a charging attack which can cause the player to be knocked backwards a tile (and potentially into a hazard). The Pinkinator boss gives birth to Bull Demons over the course of the battle. Looting her corpse yields Pinky embryos (unusable loot items), and as such it can be presumed that the Pinkinator is the progenitor of all of the "Pinky" class monsters.

Pinkies are Demons in DOOM II RPG that makes their first appearance at the UAC Administration of the UAC East Coast Facility.