Demon/Doom 3

The Demon in Doom 3 (a.k.a. Pinky) is very much different from its older versions. It has no visible nose or eyes, its horns point straight forward instead of out from the side of its head, walks on all fours, has a more animal-like appearance and has cybernetic rear legs.

It attacks in a similar fashion to its classic version by running up to the player and biting them, but due to the player's reduced movement speed, it's much harder to escape from and due to an increased attack speed an range, the attack is much harder to dodge. Additionally, being hit by an enraged Demon, throws the player's aim around, which is very confusing and makes counter attacking nearly impossible.

Like the Doom 3 version of the Imp, the Demon is tougher than its classic counterpart due to increased firepower in some of the weapons, but it still takes only around two shotgun blasts at point-blank range to kill it.

Trivia

 * In the Doom movie, the character Pinky turns into a Demon later in the film. This is evident, as the monster inherits his bionic-wheelchair contraption.