Runalen
In one manuscript of the Prose Tristan, son of King Hoel of Brittany, and the brother of Kahedins and Isolde of the White Hands.
He loved a lady named Gargeloain, and Tristan helped him arrange a tryst with the woman. Later, Gargeloain’s husband, Bedalis, tracked down Tristan and Ruvalen and mortally wounded them both with a poisoned lance.
Source
Prose Tristan | 1230-1240