"No, I don't think that Bill will be a true werewolf, but that does not mean that there won't be some contamination. Those are cursed wounds. They are unlikely ever to heal fully, and - and Bill might have some wolfish characteristics from now on."
-- Remus Lupin (HBP29)
During the Battle of the Tower in June of 1997, Bill Weasley is attacked by the werewolf Fenrir Greyback. It is not the full moon, so the wounds do not lead to full-blown lycanthropy, but Bill’s face is terribly scarred and he develops a yen for raw meat (HBP29)