Bladud or Blaiddyd[a] is a legendary king of the Britons, although there is no historical evidence for his existence. He is first mentioned in Geoffrey of Monmouth's Historia Regum Britanniae, which describes him as the son of King Rud Hud Hudibras, and the tenth ruler in line from the first king, Brutus, saying Bladud was contemporaneous with the biblical prophet Elijah.

Historia regum Britanniae, originally called De gestis Britonum, is a pseudohistorical account of British history, written around 1136 by Geoffrey of Monmouth. It chronicles the lives of the kings of the Britons over the course of two thousand years, beginning with the Trojans founding the British nation and continuing until the Anglo-Saxons assumed control of much of Britain around the 7th century. It is one of the central pieces of the Matter of Britain.