Clot
The basic enemy.
Bloat
This enemy is larger than the other zombies, and vomits acidic bile.
Gorefast
Slightly faster than clots, and swings a metallic object as it approaches.
Crawler
A spider-like zombie.
Stalker
An invisible zombie. It is detected either by the Commando, or by a barely visible halo.
Siren
A zombie in a straight jacket, who's loud scream will inflict damage on the player.
The scream is a spherical area-attack centered on the Siren, and will inflict light damage against all players within the sphere. In addition, any grenades or rockets within the area of effect are destroyed.
Scrake
Equipped with a chainsaw.
Flesh Pound
A zombie with heavy metallic arms. It is recognizable with a light on its body, which becomes red when it is attacked.
Patriarch
An intelligent zombie with a surgically attached minigun.