Former human monsters, as a conceptual family of enemy types, are humans that have been slain and reanimated, or "zombified", by the evil forces of Hell, and taken as a group they are Doom's most common enemies, especially in early levels. They were once soldiers, like the player's marine, or UAC security guards, but have been somehow turned undead and now serve the demons they once fought. Inside the Doom source code and in the Doom Bible they are called Possessed humans, and their sprite prefix always contains an abbreviation for "possessed". Because of their immediately human origin, they attack with hand-held firearms instead of innate abilities or cybernetic implants as other monsters do, and their low speed and durability makes them easier to eliminate than most of their fully demon