Sir Gareth (Old French: Guerrehet) was a Knight of the Round Table in Arthurian legend. He is nicknamed "Beaumains" in Sir Thomas Malory's Le Morte d'Arthur. He was the youngest son of Lot and of Morgause, King Arthur's half-sister, thus making him Arthur's nephew, as well as brother to Gawain, Agravain, Gaheris, and half-brother to Mordred.