Dyfnwal ab Owain (died 975) was a tenth-century King of Strathclyde. He was a son of Owain ap Dyfnwal, King of Strathclyde, and seems to have been a member of the royal dynasty of Strathclyde. At some point in the ninth- or tenth century, the Kingdom of Strathclyde expanded substantially southwards. As a result of this extension far beyond the valley of the River Clyde, the realm became known as the Kingdom of Cumbria. By 927, the kingdom seems to have reached as far south as the River Eamont.