Demon/Doom 3

The Demon (also known as Pinky) in Doom 3 has a significantly different portrayal from its classic versions, taking the appearance of a canine-like cybernetic quadrupedal demon.

The Demon has no eyes, and has small tusks on both sides of its mouth, instead of horns. The designers have explained the unique face of the Demon by describing how it's born: a newborn Demon's face is buried under thick folds of flesh (they do not undergo apoptosis, unlike other animals), and the beast must then "consume" itself in order to breathe and eat.

It walks on all fours in a canine style, and it has cybernetic rear legs, accompanied by the robotic sound effects it makes when it walks. It frequently emits a loud mechanical roar, messing with the perspective by shaking the screen.

This monster makes its debut in the Administration Complex, where the Marine enters a computer room to grant access to a nearby elevator. A demon, stationed on an overhead corridor, bends a part of the corridor's guard rail, drops downwards (destroying a ceiling lamp with a headbutt in the process), faces the marine through the massive window for a moment, and goes to the door of the room in order to take it down. After ramming the door several times, which merely dents it, the Demon smashes through the window and attacks the player.

Combat Characteristics
Despite the many changes to its appearance, it attacks in an almost similar fashion as its classic version; running up to the player to repeatedly bite or tusk them in quick succession, disorientating them in the process.

Although seemingly large and limited to forward movement, Demons can actually quickly hop sideways several feet when shot - if there is enough room for them to do so.

Tactical Analysis
The Demon, in many ways, is a lot tougher than its classic counterpart. While a single tusk attack only does moderate damage, being hit by an enraged Demon disrupts the player's aim, making counterattack much more difficult. Combined with the fact that it can combo at a faster rate, this monster can practically make short work of any unfortunate player if cornered.

Due to the player's reduced movement speed and the monster's increased attack speed and range, it is much harder to escape from a Demon than its classic version. Additionally, this 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. However, while it moves slightly faster than the player normally walks, they can be outrun by sprinting.

The best strategy to take down a Demon is to use a ranged weapon before it can close in to bite you. The Shotgun, while powerful at close range, is not a good choice, as Demons have high enough health to survive from a Shotgun blast at point-blank range, leaving the player vulnerable to the monster's counterattack. The Chain Gun and the Plasma Gun are the most effective weapons against Demons, since the bullets and plasma cells can take them down in seconds from a distance, and the Demon stops to roar when its health is depleted to a certain point, giving the player more time to attack.

In Resurrection of Evil, the Super Shotgun easily kills them with one shot, as its large size will ensure most of the pellets hit.

Trivia

 * In the original 2005 Doom film, the character "Pinky" turns into a Demon towards the end of the film. It is clearly the same character, as the monster inherits his bionic wheelchair contraption. Why he did not simply mutate into a wheelchair-equipped Imp or Hell Knight is unknown; however, one explanation is that because there is less of him to work with than normal humans, the mutation was more concentrated on his "human" anatomy.
 * In the Doom 3 E3 2002 video, in the bathroom, the Marine is hiding behind a corner as a Demon is eating the guts of a Fat Zombie on the floor. This is considered one of the most disturbing and memorable scenes in the demonstration. The Marine then emerges and destroys the Demon, taking little harm in the process. Surprisingly, the Fat Zombie then "awakens" and attacks, forcing the Marine to kill it as well. In the Doom 3 game itself, this Demon was replaced by another Zombie, making the scene even more disturbing and grotesque, as it shows the Zombies engaging in cannibalism; also, the Marine views the scene from above through a ceiling grate rather than around a corner.
 * It should be noted in some places in the Hell level of Doom 3, the organic half of this Demon can be found hanging on meat hooks. Why they are there is unknown, but it has been speculated that the more intelligent hellspawn use Demons as a food source in the same way humans use hogs. Some are skeptical, as Demons are very powerful and would disrupt the more intelligent hellspawn's attacks with its own attack, but humans have been known to hunt dangerous animals for food -- including wild boars. Demon pork was later made explicit mention of in DOOM.
 * The Laserhund of Wolfenstein II: The New Colossus and Wolfenstein: Youngblood may be a tribute to cybernetic Pinky.