A sketchy but important figure, probably an early ninth century Welsh ecclesiastic.  He was the original compiler, or possibly later editor, of the Historia Brittonum (History of the Britons), an almost random assortment of texts covering the ancestries of kings, geography, the lives of saints, and annals or chronicles. The Historia includes mentions of Julius Cæsar, Ambrosius Aurelianus, Arthur, Patrick, and other figures.