- This article is about the specific enemy. For the collective term "demons" that refers to all the enemies in Doom, see Monster.
- "Sorta like a shaved gorilla, except with horns, a big head, lots of teeth, and harder to kill. Don't get too close or they'll rip your fraggin' head off."
- ― Doom manual description
The Demon (also commonly known as the Pinky or Bull Demon) is a monster found in all classic Doom games up to date. The id Software staff has called the monster "Pinky" in reference to its coloration, especially during the development of Doom 3, when a new version of the monster was designed, although they made it grayish instead of pink. Demons and Spectres also are sometimes collectively called "pigs"; this word is used in more than 100 Compet-n submissions.
- The name of the Demon thing or object in the source code is MT_SERGEANT, as it fits into the role of a "Demon Sergeant" according to the Doom Bible in section 7.2. Correspondingly, the root of the sprite name of the monster is SARG.
- In the Doom 0.5 alpha, the Demon uses a different death animation where it stretches and distorts horizontally and explodes into a ball of yellow fire. This could have been the standard death animation, or it could have been a gib animation (when hit with explosive weaponry).
- The Demon's attacking animation shows it biting a bloody bit of flesh off its intended target regardless of whether the attack landed or not.
- The Demon, along with the Mancubus, Spiderdemon and Cyberdemon are the only monsters whose death sound clips includes noise other than the monsters' vocals; in this case, the Demon makes an audible thud when it hits the ground after it dies. This and the Mancubus are the only monsters to do so, although the Demon's is much clearer.
- Demons are capable of gibbing Zombiemen.
- In a ZDoom-based source port, if the player is killed by a Demon (monster is credited with delivering the blow that reduces player's health to 0%), an obituary message is displayed at the top of the screen: "[player name] was bit by a Demon."
In both Doom RPG and Doom II RPG, the Demon appears as the "Pinky" class of monster. There are three variations, identified by color:
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 the "Pinky" class monsters.
- Smaller than the other types in Doom II RPG; pink in the Java and BREW versions, but olive-colored in the iOS version).