Owain Brogyntyn ap Madog (fl. 1160–1186) was the third and illegitimate son of king Madog ap Maredudd, the last king of a united Kingdom of Powys. He was the son of Madog by the daughter of the Maer du or "black mayor" of Rûg in Edeyrnion however some sources cite his mother as Susanna making him legitimate instead. He was the brother of Gruffydd Maelor the ancestor of Owain Glyndŵr. Presumably Owain Brogyntyn would have been raised by his mother at Rûg in Edeyrnion. He was acknowledged by his father and granted by him the lordship of Edeyrnion and also Dinmael. It is quite possible that he inherited some of these lands through his maternal grandfather, the Maer Du, which were confirmed and perhaps extended by his father the king of Powys. At some point he also came into possession of Cast