Asclepidiot
A Briton war leader from the third century who became the choice of the Britons to overthrow the tyrant Roman king Allectus. Asclepiodotus succeeded and became king himself. He ruled fairly and justly for ten years before being conquered by Coel of Kaercolun.
Historically, Asclepiodotus was an administrator under a war general named Constantine Chlorus, who, history believes, really re-conquered Britain from Allectus.
Sources
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155