Maredudd ab Owain was a Welsh monarch, ruling in Gwynedd, Deheubarth and Powys. A member of the House of Dinefwr, his patrimony was the kingdom of Deheubarth comprising the southern realms of Dyfed and Seisyllwg. Upon the death of his father King Owain ap Hywel Dda around 988, he also inherited the kingdoms of Gwynedd and Powys, which he had conquered for his father. He was counted among the Kings of the Britons by the Chronicle of the Princes.