Mutants

Mutants are a group of mutant humanoid Monsters kept in Facility. They are listed on the Whiteboard and are bet on by the Demolition department. They are seen several times during the System Purge.

Physical Descriptions and Attributes
The Mutants appear as heavily disfigured humans, suffering from some sort of virus/infection, or are part of an experiment gone wrong. Their flesh is covered with what appear to be chemical burns or radiation scars, and what little hair they have is scraggly and tinged green.

Their behavior is similar to that of the Zombies, chasing after and attacking humans in an animalistic rage and are rather unpredictable. But instead of eating them, they vomit a thick green bile from their mouths into the faces of their victims, possibly to convert them into more mutants or to simply melt their faces via acid.

It should be noted that there are other Mutants in the Facility who look different but are still listed under the Mutant category, such as the Mutant Girl, Mutant in Hospital Gown and possibly the American Slow-Walking Creepy Girl. These Mutants wear bright orange suits and black gloves similar to HAZMAT uniforms, suggesting that they were all part of a crew responsible for handling toxic material or working in a radioactive environment.

Tampering with the gas mask in the basement will summon them.

Appearances
The Mutants along with the Mutant in a Hospital Gown are first seen in their cube cell waiting to be released. During the System Purge, a security monitor shows three Mutants hold a scientist down while another vomits the thick greenish bile as stated above into their captive's mouth.

Later, the Mutant in a Hospital Gown, attempts to kill Marty before being shot in the head. In the novelization, the Mutants take the place of the Zombies during the first wave of the purge.

Inspiration
They are a reference to mutated humans in films such as the 2006 remake of The Hills Have Eyes, the inbred and feral Mountain Men in Wrong Turn, and the mutants from Chernobyl Diaries. They bear similar characteristics, however, to the Rage Virus based zombies such as the ones from 28 Days Later, Signal and the ones infected with the the Sicko Virus from Planet Terror. Some infected within the Left 4 Dead universe also wear contamination suits similar to these. The alien slug-controlled undead from Slither also had a corrosive spit they would use on their victims.