In the Vulgate Cycle, a daughter of Leodegrance, and the half-sister and double of Guinevere. They were both born on the same night, but the False Guinevere was born to the wife of Leodegrance's seneschal. The enemies of their father attempt to kidnap Guinevere on her wedding night and substitute her for the False Guinevere, but their plan is foiled.
The False Guinevere later tricks Arthur into believing that he is her husband by claiming that her half-sister is not the woman Arthur married. When she becomes ill she confesses her deceit and Arthur returns to the true Guinevere.
- Lacy, Norris J., ed. (1996). The New Arthurian Encyclopedia. New York: Garland.