The male specimen are all clones of Kevin Clamely's deceased son, produced by the Clot Mother. The female specimen were initially created at a separate facility and are believed to be clones of Kevin Clamely's (still-living) daughter, Rachel. Hence Kevin Clamely's assumed title of "The Patriarch" and his references to the specimen as his "children."
The initial outbreak occurred in London, but has since spread all over Europe and possibly the entire world. Kevin Clamely has facilities hidden everywhere, and with a near endless supply of clones at his disposal he is a threat to all remaining humans.
- Cyst (Killing Floor 2)
- Rioter (Killing Floor 2)
- Slasher (Killing Floor 2)
- Elite Crawler (Killing Floor 2)
- Gorefiend (Killing Floor 2)
- Quarter Pound (Killing Floor 2)
- The Patriarch
- Dr. Hans Volter (Killing Floor 2)
- King Fleshpound (Killing Floor 2)
- Abomination (Killing Floor 2)
- Abomination Spawn (Killing Floor 2)
- Vile Matron (Killing Floor: Incursion)
- Infected Soldier (existed in the original mod until version 2.0)
- Wretch (existed in the original mod until version 2.0)
- Gunpound (ranged variation of the Fleshpound intended for the original mod, but was never released)
- Shade (intended for the original mod, but had it's assets used for Crawler and Stalker instead)
- The Matriarch (a rumored boss for Killing Floor 2)
- The term Zeds may come from the British film Shaun of The Dead where the zombies are referred to as Zeds which is the British pronunciation of the letter "Z."