Rivalon was the son of Tanguy d'Hennebont but his mother is unknown. The date and place of his birth have not been found.
Rivalon d'Hennebont
Tanguy d'Hennebont (-<1114)
Guegon d'Hennebont (c1067-?)
Huelin d'Hennebont (-<1066)
Avan de Cornouaille (->1037)