Custenin Gorneu, that is Constantine of Cornwall, is a figure in Welsh genealogies, a descendant of Cynan the reputed lord of the earliest British settlers in Little Britain and the father of Erbin, father of Gereint. The Latin name Constantinus normally changes to Custennin in Welsh. In some later versions of these genealogies, e.g. Mostyn 117, he is made to be also the father of Uthyr Penndragon (Uther Pendragon), the father of Arthur, thus identifying him with the Geoffrey’s King Constantine of Britain.