Ferals are villains who embrace a savage, animalistic lifestyle or belief system.

Sometimes, a feral may actually be an Animal, but in order to qualify, they must be of the anthropomorphic kind (such as General Woundwort) in an environment or world where their savage behavior is seen as abnormal rather than the norm.

Humans (or humanoids) can also count as Ferals if they have devolved into a state of wild abandon beyond even that of a "barbarian", often to the point they lose their ability of speech, their grip on their sanity and/or reality and experience delusions (in this case of that of an animal), adapt dangerous and murderous tendencies and engage in vicious, anti-social behaviors that are more akin to animals than humans - in fact, many times feral humans engage in even more depraved acts than most animals (such as incest and cannibalism): they are also guided largely by instinct, thus they tend to be chaotic in nature. Examples include Jack Merridew, Roger, Sylar and Ezekiel.

Nevertheless, it is quite possible to be at the same time feral and sophisticated. Examples of this are Jenner and Professor Ratigan.