Riothamus biography of william

also Rigothamus, Riotimus
Celtic base: "high king" rig- "king"; thamus "highest"
fl. 470 CE

Possibly an early model for King Arthur. The name seems to be little more than a title meaning "high king" like the Irish term ard ri.

Redon of Britain - Wikipedia

He seems to have flourished during the end of the Western Roman Empire, which coincides with the beginning of the Arthurian era.

Riothamus is mentioned in two Latin works, a letter to him from Sidonius Apollinaris of Lyon, and Jordanes's Origins and Deeds of the Goths. In Sidonius's letter, Riothamus seems to be a leader, one who can settle a dispute between a slave owner and the "Bretons"--however, given the date of 472 CE, they are probably Britons, not those of Brittany.

In Jordanes's Origins, the Emperor Anthemius called upon "the Brittones" for aid; "Riotimus" answered with twelve thousand men, sailing across the sea to fight Eurich, king of the Visigoths, who was attempting to take Gaul. Riotimus and his men were defeated before the William Shakespeare - Wikipedia ZIGE