Gwenwynwyn ab Owain Cyfeiliog (died c. 1216) was the last major ruler of mid Wales before the completion of the Norman English invasion.
[3] Owain Cyfeiliog had been a notable poet as well as a leader of the resistance against English invasion, and chose to enter the abbey of Strata Marcella in later life; he died in 1197, two years after becoming a monk.
Gwenwynwyn continued his father's strategy and is thought to have been one of the Welsh rulers who made an agreement with King Richard I of England not to attack his kingdom while he was away on crusade.
In 1202 there was an uneasy peace between the two Welsh princes as Gwenwynwyn began attacking Marcher lords, thus losing John's favour; this eventually resulted in his being imprisoned at Shrewsbury.
He was succeeded by Gruffydd ap Gwenwynwyn, his son by Margaret Corbet, who was eventually restored to his lands after Llywelyn's death, and continued to feud with the princes of Gwynedd.