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 and
Bede, partly from Welsh genealogies and saints' lives, partly from sources now lost and unidentifiable, and partly from his own imagination (see bibliography). Several of his kings are based on genuine historical figures, but appear in unhistorical narratives. A number of
Middle Welsh versions of Geoffrey's
Historia exist. All post-date Geoffrey's text, but may give us some insight into any native traditions Geoffrey may have drawn on.