The Demon is a big, bulky, pink monster with a big head and an equally big mouth filled with sharp teeth. It loves to run up to people and chomp them to bits. The developers at id Software took to calling the Demon "Pinky" because of its coloration. Some have also called Demons (and their invisible counterparts the Spectre) "pigs," most likely due to their coloration and the pig-like squeal they let out when killed.
The Doom manual describes Demons as "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."
While still considered "Pinky," the Demons in Doom 3 are considerably different in appearance to the original Doom Demons. It has no visible eyes, its horns point straight forward instead of out from the side of its head, it walks on all fours in a canine style, and it has cybernetic rear legs. It roars frequently, messing with the player's perspective by shaking the screen. Despite its aesthetic changes, the Demon still attacks in more or less the same fashion as its classic version: running up to the player and biting them. However, due to the player's reduced movement speed and the monster's increased attack speed and range, it is much harder to escape a Doom 3 Demon than a classical Demon. Additionally, the Doom 3 Demon is shorter but bulkier than its classic counterpart, a fact which, combined with Doom 3's more cramped corridors, makes it tougher - if not impossible - to dodge around it.
Powers & Abilities
While Demons do not have a ranged attack, they have a huge advantage over many of their demonic counterparts: speed. They can outrun many of the other adversaries in Doom, closing distances very quickly, often running towards the player in a zig-zag pattern - making it harder to hit - and helping to corner the player. Their attacks do a rather minimal amount of damage, but the frenzied pace at which they do it more than makes up for it. In Doom 3, Demons are also able to throw off a player's aim by roaring.
In the 2005 Doom movie, a character known by the name "Pinky" mutates into the Doom 3 Demon. Due to Pinky having a bionic wheelchair in place of his legs however, this Pinky Demon has wheels instead of bionic hind legs.