Legend Of The Werewolf (1975)

aka: Plague Of The Werewolves

In 19th century France, a traveling circus adopts a boy who was raised by wolves. Later as an adult (David Rintoul), he kills one of the other circus workers and runs away to Paris. There he gets a job in a rundown zoo and falls for a girl (Lynn Dalby) who works in the local brothel. He resents her clients and whenever the moon is full he exacts his revenge on them by committing gruesome murders. Also with Peter Cushing, Ron Moody, Hugh Griffith and Roy Castle.