king of Gwynedd and Powys (1039–63). The son of Llywelyn ap Seisyll, king of Gwynedd, and Angharad, the king of Deheubarth's daughter, Gruffydd created a personal dominion over much of Wales in alliance with English and Scandinavians. He won Gwynedd and Powys in battle (1039) and defeated the Mercians on the river Severn. His conquests in Deheubarth took longer (1040–55), during which he slew two of its kings. His alliance with Earl Ælfgar of Mercia, whose daughter he married, sustained a long struggle with Harold Godwineson (later Harold II). Harold's attack on Gruffydd's court at Rhuddlan (1062) caused him to flee, and soon afterwards (5 August 1063) he was killed by his own men.
Subjects: British History.