Real World Origin:
Film, The Wolf Man (1941)
When Larry Talbot returns to his home in Wales, he comes across the local werewolf legend:
Even a man who is pure in heartOne night Larry is attacked by what he believes is a wolf. Although he is bitten, he manages to kill the wolf with his new silver-headed cane. As revealed by a gypsy fortuneteller, the animal that bit Larry was actually the gypsy's son, who had been a werewolf. Now Larry shares the creature's curse.
and says his prayers by night
may become a wolf when the wolfbane blooms
and the autumn moon is bright.
Larry Talbot discovers the truth of the fortuneteller's statement when, on the next full moon, he turns into a monster that is half man and half wolf. Soon the Wolf Man begins terrorizing the countryside and killing the unwary. When Larry returns to his human form the next morning, he tries to convince his father of his unfortunate condition and that he poses a threat to the village. His father refuses to believe this superstition and ties Larry up while the peasants hunt the wolf. Surely his son will be convinced of his madness when the real wolf is found and killed. However, when the full moon rises, the Wolf Man breaks his restraints and again goes on the hunt.
The Wolf Man was not the first film to feature a wolf man (that was Werewolf of London (1935)), but it was one of the most influential. A good portion of werewolf lore found in films and novels today are derived from The Wolf Man rather than from the various werewolf legends found worldwide.
The folklore of werewolves was well-known in medieval Europe, although the legends varied from place to place. Even the method by which a person could become a werewolf was not consistent. One of the most common beliefs was that werewolves were witches who used their magic to transform themselves. Only occasionally could one unwittingly become a werewolf through some sort of curse. The European werewolf was usually described as being nearly indistinguishable from a natural wolf with a few differences; e.g., lacking a tail, having human eyes, or having a human voice.
A variety of legends in the Americas were analogous to European folklore. The best known legend is that of the Navajo Skinwalkers. In the Skinwalker legends, a Navajo witch could transform himself into an animal using magic and the skin of the animal into which he wanted to transform. Unlike European werewolves, Skinwalkers were not limited to the form of a wolf.
While borrowing somewhat from existing legends, The Wolf Man and its sequels introduced or popularized certain elements that are taken for granted in modern werewolf films and stories. These include becoming a werewolf by being bitten by one, vulnerability to silver, the transformation into a werewolf occurring under a full moon, and the werewolf as being a mixture of wolf and man rather than being a slightly atypical wolf.
Current films, including the 2010 remake of The Wolf Man, have taken advantage of advanced makeup and special effects techniques and have made their werewolves more animalistic than those shown in Werewolf of London or the original Wolf Man.