Goryon
Father of Arthur’s warriors Culfanawyd, Huabwy, Cador, Uchei, and Seidi in various Welsh tales.
Gorlois, the father of Cador in a Welsh adaptation of Geoffrey of Monmouth, may be a variation of his name.
Sources
Culhwch and Olwen | Late 11th century
Geraint and Enid | 13th century
Triads of the Island of Britain (Welsh ”Triads”) | 11th century to 14th century