Book of Were-Wolves - By Sabine Baring-Gould – Their History and Folklore. The werewolf, also known as a lycanthrope, is a mythological or folkloric human with the ability to shapeshift into a wolf or a therianthropic hybrid wolf-like creature, either purposely or after being placed under a curse or affliction (e.g. via a bite or scratch from another werewolf). Early sources for belief in lycanthropy are Petronius and Gervase of Tilbury. The werewolf is a widespread concept in European folklore, existing in many variants which are related by a common development of a Christian interpretation of underlying Indo-European mythology which developed during the medieval period. From the early modern period, werewolf beliefs also spread to the New World with colonialism.