Llywelyn ab Iorwerth, also known as Llywelyn the Great, was a medieval Welsh ruler. He succeeded his uncle, Dafydd ab Owain Gwynedd, as King of Gwynedd in 1195. By a combination of war and diplomacy he dominated Wales for 45 years.
Dolwyddelan Castle was built by Llywelyn; the old castle nearby may have been his birthplace.
Seal of Llywelyn ap Iorwerth, used on official documents