Tristan the Younger, King of Lyonesse
Arthurian Literary Character

Tristram the Younger was the legendary son of Tristram the Elder, King of Lynosse, by Isolde of Ireland. He was supposedly born and raised at the Cornish Court. He spent some time at the court of the aging King Arthur, where Queen Guinevere took quite a fancy to him. However, he rejected her and eventually married his sister-in-law, Princess Maria, the sister of King Juan of Castile. It may have been during his reign that Lyonesse was inundated by the sea.