The title King of the Britons (Latin: Rex Britannorum, Welsh: Brenin y Brythoniaid) was used (often retrospectively) to refer to the most powerful ruler among the Celtic Britons, both before and after the period of Roman Britain up until the Norman conquest of England.The Britons were the Brittonic-speaking peoples of what is now England, Wales, and southern Scotland, whose …

The following list of legendary kings of Britain derives predominantly from Geoffrey of Monmouth's circa 1136 work Historia Regum Britanniae ("the History of the Kings of Britain"). Geoffrey constructed a largely fictional history for the Britons (ancestors of the Welsh, the Cornish and the Bretons), partly based on the work of earlier medieval historians like Gildas, Nennius …