In Arthurian legend, Morgause or Morgase (also known as Anna or Anna-Morgause) is the half-sister of King Arthur who slept with him and produced Mordred, the heir who would bring Camelot's downfall. She is the daughter of Gorlois, Duke of Cornwall and Lady Igraine. She is married to King Lot, an enemy of Arthur in the rebellions following Arthur's coronation.