Werewolves are mythical creatures that are part human, part wolf. Although they look like a regular person most of the time, they transform into an uncontrollable beast under a full moon.
In a bid to create a bride for Chuck D. Head, Professor Frank N. Stein created Daphne, but accidentally used a werewolf brain. This mistake wasn't spotted until Chuck took Daphne to the roof of Castle Frank N. Stein whilst a full moon was out. Daphne quickly transformed and attacked Chuck. Oddly, she didn't seem to know she was a werewolf and was worried that the full moon could have altered Chuck.
A variation of a werewolf is the Werehog, a transformation of Sonic the Hedgehog that featured prominently in Sonic Unleashed.