Rhys ab Owain was a king of Deheubarth in southern Wales.

Rhys was the son of Owain ab Edwin of the line of Hywel Dda

Hywel Dda

Hywel Dda , was the well-thought-of king of Deheubarth in south-west Wales, who eventually came to rule Wales from Prestatyn to Pembroke. As a descendant of Rhodri Mawr, through his father Cadell, Hywel was a member of the Dinefwr branch of the dynasty and is also named Hywel ap Cadell...

, and member of the Dinefwr

Dinefwr

Dinefwr was a local government district of Dyfed, Wales from 1974 to 1996. It was named after Dinefwr Castle which was the royal capital of the Principality of Deheubarth and one of the three principal royal courts of Wales....

 dynasty. He followed his brother Maredudd

Maredudd ab Owain ab Edwin

Maredudd ab Owain ab Edwin was a prince of the kingdom of Deheubarth in south west Wales.Maredudd was the son of Owain ab Edwin and of the line of Hywel Dda...

 as king of Deheubarth in 1072. Together with the nobility of Ystrad Tywi

Ystrad Tywi

Ystrad Tywi is an area of south-west Wales situated on the banks of the Tywi river as it approaches the sea to join the Bristol Channel at Carmarthen...

, he was implicated in the killing of Bleddyn ap Cynfyn

Bleddyn ap Cynfyn

Bleddyn ap Cynfyn was a Prince of the Welsh Kingdoms of Gwynedd and of Powys.- Lineage :Bleddyn was the son of Princess Angharad ferch Maredudd with her second husband Cynfyn ap Gwerstan, a Powys Lord, about whom little is now known...

 king of Gwynedd

Kingdom of Gwynedd

Gwynedd was one petty kingdom of several Welsh successor states which emerged in 5th-century post-Roman Britain in the Early Middle Ages, and later evolved into a principality during the High Middle Ages. It was based on the former Brythonic tribal lands of the Ordovices, Gangani, and the...

 and Powys in 1075.

In 1078 he was defeated by Trahaearn ap Caradog

Trahaearn ap Caradog

- Accession:On the death of Bleddyn ap Cynfyn in 1075, it appears that none of his sons were old enough to claim the throne, and Bleddyn's cousin Trahaearn ap Caradog, seized power...

, who had followed Bleddyn on the throne of Gwynedd, in a battle at Gwdig. Later the same year Rhys was killed by Caradog ap Gruffydd

Caradog ap Gruffydd

Caradog ap Gruffydd was a Prince of Gwent in south-east Wales who made repeated attempts to gain power over all of southern Wales by seizing the Kingdom of Deheubarth.- Lineage :...

 of Gwent. His defeat and death were hailed in the annals as "vengeance for the blood of Bleddyn ap Cynfyn".

Rhys was followed as king of Deheubarth by his second cousin, Rhys ap Tewdwr

Rhys ap Tewdwr

Rhys ap Tewdwr was a Prince of Deheubarth in south-west Wales and member of the Dinefwr dynasty, a branch descended from Rhodri the Great...

.