Mutants are the first enemies encountered in the game. These creatures are humans who were heavily irradiated with Element 99 energy, which appears to have mutated them into tall, emaciated and aggressive monstrosities. They also seem to be able to survive with only their top half intact as, Nathaniel Renko comes out of a vent and is attacked by one that only has the front part of its torso, its arms, and its head still attached. Mutants are one of the only non-boss creatures to not appear in multiplayer along with the Zek medics.
Mutants are pink and warty. They are skinny and very fragile and, despite their thin appearence, are very slow.
Mutants are considered very easy to fight. They are very slow and don't seem to have any time manipulation abilities but they will charge you at times.. All they can do is claw at you and climb up walls. An accurate Pistol shot to the head will easily kill one.