Gruffudd ap Cynan (c. 1055–1137) was King of Gwynedd from 1081 until his death in 1137. In the course of a long and eventful life, he became a key figure in Welsh resistance to Norman rule.
As a descendant of Rhodri Mawr (Rhodri the Great), Gruffudd ap Cynan was a senior member of the princely House of Aberffraw. Through his mother, Gruffudd had close family connections with the Norse settlement around Dublin and he frequently used Ireland as a refuge and as a source of troops. He three times gained the throne of Gwynedd and then lost it again, before regaining it once more in 1099 and this time keeping power until his death. Gruffudd laid the foundations which were built upon by his son Owain Gwynedd and his great-grandson Llywelyn ab Iorwerth (Llywelyn the Great).