A werewolf (Old English: werwulf, “man-wolf”) or occasionally lycanthrope is a mythological or folkloric human with the ability to shapeshift into a wolf (or, especially in modern film, a therianthropic hybrid wolflike creature), either purposely or after being placed under a curse or affliction (often a bite or scratch from another werewolf). Early sources for belief in this ability or affliction, called lycanthropy, are Petronius (27–66) and Gervase of Tilbury (1150–1228).