(French, loup-garou). A bogie who roams about devouring infants, sometimes under the form of a man, sometimes as a wolf followed by dogs, sometimes as a white dog, sometimes as a black goat, and occasionally invisible. Its skin is bullet-proof, unless the bullet has been blessed in a chapel dedicated to St. Hubert. This superstition was once common to almost all Europe, and still lingers in Brittany, Limousin, Aurergne, Servia, Wallachia, and White Russia. In the fifteenth century a council of theologians, convoked by the Emperor Sigismund, gravely decided that the loup-garou was a reality. It is somewhat curious that we say a “bug-bear,” and the French a “bug-wolf.” (“Wer-wolf” is Anglo-Saxon wer, a man, and wolf - a man in the semblance of a wolf. “Gar” of gar-ou is wer or war, a man; and “ou,” a corruption of orc, an ogre.)
Ovid tells the story of Lycaon, King of Arcadia, turned into a wolf because he tested the divinity of Jupiter by serving up to him a “hash of human flesh.”
Herodotus describes the Neuri as sorcerers, who had the power of assuming once a year the shape of wolves.
Pliny relates that one of the family of Antaeus was chosen annually, by lot, to be transformed into a wolf, in which shape he continued for nine years.
St. Patrick, we are told, converted Vereticus, King of Wales, into a wolf.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894