Morgan (The Creation of Camelot)

Morgan was the half-sister of King Arthur and mother of Mordred.

Biography
A year after the Master arrived in Camelot and became Arthur's new Merlin, Morgan gave birth to Mordred in Lothian. When he heard about this, Arthur sent the Master to track them down and kill Mordred. As part of his plan the Master allied with Morgan to help raise Mordred so when he grew up he could kill Arthur at the battle of Camlan so Britain could never become one country. The Master fooled Arthur into thinking that Morgan and the Master were enemies and that Mordred was dead. (DWA: The Creation of Camelot)