This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Werewolf (Worldwide)
In folklore, a werewolf[a] (from Old English werwulf 'man-wolf'), or occasionally lycanthrope is an individual who can shape-shift into a wolf, either purposely or after being placed under a curse or affliction (often a bite or the occasional scratch from another werewolf), with the transformations occurring on the night of a full moon.
The beliefs classed together under lycanthropy are far from uniform, and the term is somewhat capriciously applied. The transformation may be temporary or permanent; the were-animal may be the man himself metamorphosed; may be his double whose activity leaves the real man to all appearance unchanged.