Guinevere

Guinevere was a female legendary character found in the Arthurian legend.

She was wife of King Arthur, and also mistress of Lancelot. She was the most beautiful of woman, conceived a guilty passion for Lancelot, one of Arthur's knights, and married Modred, her husband's nephew, in the latter's absence on an
expedition against the Romans, on hearing of which he returned, met Modred on the field of battle, whom he slew, fell mortally wounded himself, while she escaped to a nunnery. Tennyson gives a different version in his "Idylls."