Voluntary and Involuntary:--

A distinction is often made between voluntary and involuntary werewolves.

The former are generally thought to have made a pact, usually with the Devil, and morph into werewolves at night to indulge in mischievous acts.

Involuntary werewolves, on the other hand, are werewolves by an accident of birth or health. In some cultures, individuals born during a new moon or suffering from epilepsy were considered likely to be werewolves.