Dark Willow

Dark Willow is a commonly used epithet for Willow during the last four episodes of Season 6, during which she absorbs dark magics in a quest to avenge Tara's death at the hands of Warren Mears, and ends up fighting her friends and trying to destroy the world. The name "Dark Willow" is never spoken on the show, but it is used extensively by fans as well as the show's creators to refer to Willow during this time.