Llywelyn's Great Seal A stone corbel from Llywelyn's castle at Deganwy, thought to be a likeness of Llywelyn Fawr, ab Iorwerth 1170s births 1240 deaths Year of birth uncertain Monarchs of Gwynedd House of Aberffraw Burials at Aberconwy Abbey 12th-century Welsh monarchs 13th-century Welsh monarchs Welsh princes