King of Gwynedd (547-586)
Born c495 Died 586
He was the son of Maelgwyn ap Cadwallon and became king of Gwynedd on his father's death from the plague, in the year 547 according to the Annales Cambriae. Known like as his father by the epithet 'Hir' or Rhun Hir, literally 'Long Rhun' or 'Rhun the Tall'.
The tale is told that Rhun's succession to the throne was disputed, on the grounds of his illegitimacy, by a minor royal from the house of Strathclyde named Elidyr Mwynfawr who claimed the throne for himself by virtue of his marriage to Maelgwyn's daughter. Elidyr Mwynfawr launched an invasion of Gwynedd but was defeated and killed by Rhun in the battle of Cadnant Brook. Rhydderch Hael, the king of Strathclyde then attacked Gwynedd seeking revenge for his cousin's death; he too was repulsed. Rhun then launched his own retaliatory raid north on Strathclyde and helped his half brother Bridei mac Mailcon secure the throne of the Picts.
As history this tale is all stuff and nonsense. For one thing Brythonic succession law had no concept of illegitimacy per se and for another thing women were ignored from the point of view of inheritance altogether. It has all the hallmarks on a tale invented at a much later date to portray Rhun as a succesful warrior king and intended for domestic political consumption in magnifying the noble deeds of the house of Maelgwyn.
Other than that nothing much is really known of Rhun or his reign. He is believed to have died in the year 586, presumably of natural causes since he would have been aged around 90 at the time, and was succeeded by his son Beli ap Rhun.