Sir Meliant de Lis (or Lile) - sometimes 'of the Rock' - was the son of King Norrois (alias Gilbert) of Lis (and Lord of the Waste Manor). He was brother of Lady Guilorete, Sir Brandelis, Gyamoure and Tyrry; as well as nephew of King Bagdemagus of Gore. His father was killed by Sir Lancelot when Meliant was young and his upbringing was entrusted to Sir Tibaut of Tintagel. While he was a squire, Meliant fell in love with Tibaut's eldest daughter, Obie. She would not have him, however, until he became a knight and challenged her father to a tournament. On the appointed day, however, Gawain arrived and championed Tibaut, unhorsing Meliant and taking him captive to the younger sister, Obilot the Maid with the Little Sleeves. The foster father and son were afterwards reconciled.

Meliant entered the Grail Quest as the squire of his uncle, King Bagdemagus, but deserted him for Sir Galahad at the White Abbey. The latter knighted him and the two rode together until they came to a perilous crossroads. Meliant chose the left fork signposted for honourable knights only; but soon found himself badly wounded by an unknown knight when he stole a golden crown from a woodland bower. Luckily, Galahad turned up to carry him off to the ministrations of an elderly monk. He did recover and was present when Galahad completed the Quest at Corbenic. Back at court, Meliant was made a Knight of the Round Table. Chrétien de Troyes lists him as the seventh best knight at Arthur's Court. He was certainly one of the only knights to ever have crossed to Sorelais via the dangerous North Welsh Bridge. Sir Meliant married Princess Florée, the daughter of King Alain of Escavalon. He fought for Arthur at the Siege of Logres Castle; but, later, as with Sir Kay, the two seem to have fallen out. Meliant and Kay joined forces with Brian of the Isles in Brittany and led an invasion of Britain. Sir Lancelot mortally wounded Meliant at Battle of Pennevoiseuse and he died soon afterward. Others versions of his story, indicating that he joined Lancelot's party and was exiled as the Earl of Tursaud, seem unlikely in light of the circumstances of his father's death.

He may be identical to Sir Meliot de Logres, although their fathers differ and they sometimes appear in company together.