Dumnagual I of Alt Clut or simply Dumnagual Hen ("the Old") was the ruler of Alt Clut (modern Dumbarton Rock), probably sometime in the early sixth century. According to the Harleian genealogies, he was the son of a Cinuit, the son of King Ceretic of Alt Clut. He is known to have fathered several sons, including the future King Clinoch and Guipno, the father of the future king Neithon of Alt Clut. (Wikipedia)