The Wolf Man 1941

https://www.imdb.com/title/tt0034398/
Director: George Waggner
Writer: Curt Siodmak
"Even a man who is pure at heart/And says his prayers by night/May become a wolf when the wolf-bane blooms/And the moon is full and bright." Upon first hearing these words, Larry Talbot (Lon Chaney Jr.) dismisses them as childish federal. After all, this is the 20th Century; how can a human being turn into a werewolf? Talbot soon learns how when he attempts to rescue Jenny Williams (Fay Helm) from a nocturnal attack by a wolf. Collapsing, Talbot discovers upon reviving that Jenny is dead-and, lying by her side, is not the body of a beast, but of a gypsy named Bela (Bela Lugosi). The son of fortune teller Maleva (Maria Ouspenskaya), Bela was a Lycanthrope, or "wolf man." And now that he has been bitten by Bela, Talbot is cursed to suffer the torments of the damned whenever the moon is full.