Gruffudd ap Llywelyn ap Iorwerth was the Welsh first-born son of Llywelyn the Great. His mother Tangwystl probably died in childbirth.

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.