Malgiers, Maugys, Mauugeys
A powerful knight who lusted after a fairy called the Maiden of the White Hands or the Dame d’Amour.
The Maiden had decreed that any knight who could defend her island, called the Golden Isle, for seven years, against any knight who passed that way, could marry her. Malgier set his sights on accomplishing the goal, although he was so loathsome that the Maiden would have found some way to get out of the marriage anyway.
After five years, he had killed 140 knights and seemed undefeatable, but he was finally killed by Gawain’s son Guinglain.
Sources
Le Bel Inconnu | Renaut de Bâgé, 1185–1190
Lybeaus Desconus | Thomas Chestre, late 14th century