The following are enemies in the id Software first-person shooter computer and video game Doom, The Ultimate Doom, Doom II and Final Doom. Most of these enemies also make appearances in Doom 64 and Doom RPG. Most of the enemies in the games are Demon from Hell; otherwise they are possessed, undead humans. Many of these creatures have become iconic in computer gaming. In the Doom novels, the creatures are initially thought to be demons, but are later revealed to be an alien race bent on the conquest of Earth. (Although this is only in the novels, and as such is not canon.)
Former humans and sergeants will close the distance on their foe, and then circle, pausing every few steps to fire a shot. Commandos, however, once within line of sight of their foe, will continuously fire their chaingun, only rotating to adjust to their target's movements. Moving out of their line of sight, such as hiding behind a wall or using a lift, will break their lock and cease their firing, and they will be on the move to seek out their foe.
Read more about Cyberdemon at Wikipedia ...
Official Site: id Software
Links: Wikipedia: Cyberdemon Doom Wiki: Cyberdemon Doom2.net: Cyberdemon