The daughter of Ygerna and Gorlois, the Duke of Cornwall and therefore half-sister to Arthur. She marries Lot of Orkney and their sons are Gawain, Gaheris, Agravain, and Gareth. In the Vulgate cycle, Malory and other later versions, Mordred is also her son by Arthur. Though unaware of it at the time, Arthur has committed an incestuous act which serves to emphasize Mordred's role as Arthur's nemesis. Morgause later has an affair with Lamorak de Galis and she is slain by her son Gaheris who discovers the two in bed.