Werewolves are mythological or folkloric people with the ability to shapeshift into a wolf or wolf like creature, either purposely by magic, or after being placed under a curse. The medieval chronicler Gervase of Tilbury associated the transformation with the appearance of the full moon; however, there is evidence that the association existed among the Ancient Greeks, appearing in the writings of Petronius. Some modern speculation has suggested that the belief in werewolves (and vampires) may stem from real medical cases of people suffering from porphyria.
