Morgan Le Fay is Arthur's half- sister. She is, therefore, the daughter of Igraine and Gorlois. She is often referred to as a fay or fairy. However, there is some confusion as to her origin; Malory believed she was indeed Arthur's half-sister, but other writers believed her to be a niece of Arthur. A rival of Guinevere, she is the old hag in Sir Gawain and the Green Knight who creates the supernatural action to frighten the queen to death; she may also be a model for the magical hag in "The Wife of Bath's Tale," who transforms herself into a beautiful maiden. In some epic stories, she is accused of causing the downfall of Arthur's Kingdom by conceiving a child with Arthur in an incestuous relationship with him. This child, Mordred, becomes the foremost rival of Arthur for the kingdom of England. She is also blamed for the imprisonment of Merlin, Arthur's magician, from whom she learned most of her magic.