- "Just a few days ago, you were probably swapping war stories with one of these guys. Now it's time to swap some lead upside their head."
- ― Doom instruction manual
The Zombieman (also known as Trooper, Former Human, Marine Private or, sometimes, Former Soldier in the game manuals) is a possessed and/or undead former soldier which has been turned into a zombie during the invasion from Hell, encountered in the classic generation of Doom, Doom II, and Final Doom.
- The Zombieman has the type name MT_POSSESSED in the Doom source code, and the sprite prefix POSS, while the analogous MT_TROOP and TROO are given to the Imp. The Zombiemen were called "demon-possessed humans" (or simply "possessed humans") in the Doom Bible (section 7.2), being "possessed in their sleep".
- With only 20 hit points, the Zombieman can be gibbed with the berserk fist, rockets, the plasma rifle, the BFG9000 (both ball and tracer), exploding barrels, Demon bites, Cacodemon ranged and melee attacks, Hell Knight/Baron of Hell clawing and ranged attacks, Revenant rockets, Arch-vile fire attacks, and--on rare occasions--Imp fireballs or melee attacks, a chainsaw's blade and even other Zombiemen. This means this monster has more ways of being gibbed than any other monster.
- In a ZDoom-based source port, if the player is killed by a Zombieman (monster is credited with delivering the blow that reduces player's health to 0%), an obituary message is displayed at the top of the screen: "[player name] was killed by a Zombieman".
In Doom RPG, the Zombieman appears as the "zombie" monster class. There are three different forms, identified by color:
They are weak against axe attacks.
- In Doom II for the Game Boy Advance, a red blood splatter, half-way covered in green, appears in the Zombieman's death animation.
- Their rifles were at one point accessible to the player (as their original starting weapon)
- In the novels, the Rifle is known as the M-211 SIGCOW, and uses 10mm rounds.
- In PlayStation Doom, their gunshot damage is increased somewhat, up to a maximum damage of roughly 21. The manual also lists the name of this enemy type as "Former Soldier", as opposed to "Former Human" as in the PC versions' manuals (or "Zombieman" as in the enemy cast at the end of the game).