Demon/Doom RPG

In both Doom RPG and Doom II RPG, the Demon appears as the "Pinky" class of monster.

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

A Pinky will attack automatically the moment the player steps into an adjacent square, even if it has already moved that turn. They are resistant to rockets but susceptible to shotgun attacks.

Also in Doom II RPG, in addition to a regular biting attack, each of the "Pinky" class monsters has 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 its 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.

Pinky is a demon in Doom II RPG that makes its first appearance at the UAC Administration of the UAC East Coast Facility.