King Lot, also spelled Loth or Lott, is a British monarch in Arthurian legend. He was introduced in Geoffrey of Monmouth's pseudohistorical Historia Regum Britanniae as King Arthur's brother-in-law, who serves as regent of Britain between the reigns of Uther Pendragon and Arthur. He has appeared regularly in works of chivalric romance, alternating between the roles of Arthur's enemy and ally, and is often depicted as the ruler of Lothian and either Norway or Orkney. His literary character is probably derived from hagiographical material concerning Saint Kentigern, which features Leudonus as king of Leudonia and father of Saint Teneu.

Gareth is a Knight of the Round Table in Arthurian legend. He is the youngest son of King Lot and Queen Morgause, King Arthur's half-sister, thus making him Arthur's nephew, as well as brother to Gawain, Agravain and Gaheris, and either a brother or half-brother of Mordred. Gareth is particularly notable in Le Morte d'Arthur, where one of its eight books is named after and largely dedicated to him, and in which he is also known by his nickname Beaumains.