Ruawn Pebyr
Rhufawn befr
Son of Dorath and is probably identical with a northern british prince or hero. There are several mentions of the name Ruawn and a prince who died young.
He is one of the Three Fair Princes of the Island of Britain in Triad no. 3. Rhonabwy says he is an advisor to Arthur and a brilliantly clad horseman.
Culhwch | The Legend of King Arthur