Werewolves, also known as lycanthropes, are mythological or folkloric people with the ability to shapeshift into a wolf or wolflike creature, either purposely, by using magic, or after being placed under a curse. The medieval English 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, a Roman chronicler.
There were several anti-werewolf panics in Europe during the Middles Ages, often running concurrently with anti-witch hysteria, which lead to the conviction and execution of a number of people for mass murder and other crimes committed while in the form of a wolf. Modern scholarship has posited that werewolves were used as an explanation for serial killers, or that confessed werewolves suffered from mental problems. Others have suggested werewolves as cover for political and religious persecutions.
Despite this rich history of lore, most people's conception of werewolves has more to do with their depiction in films. In addition to the full moon, which movies had cemented as a the only "trigger" for the transformation, Hollywood has is also responsible for the idea that werewolves could only be killed by silver, which only first appeared in the 1941 film, The Wolf Man.
Werewolvism was an involuntary condition brought on by the full moon. At dawn, the individual would revert to human form. While a wolf, the individual retained human intelligence and memory and could refrain from bloody attack on others. If injured, the wound would heal with remarkable speed.
The condition would begin expressing itself on the onset of puberty. An adolescent named Dieter, who lived in Cologne, began transforming in early 1176. While he took precautions to isolate himself from others while in wolf-form, one night, he transformed in public, and was pursued by the townsfolk, until he was given shelter in the towns Jewishquarter by man named Avram.
A werewolf named Warren Z. Wolfe briefly hunted in the East End of London in the late 19th century. He killed at least one old woman the first night of the harvest moon. However, he was confronted and killed in his wolf form the following night while he hunted in Limehouse. His killer, a man named Harris, stabbed Wolfe to death with the silver ferrule of his umbrella.