Gruffudd ap Cynan (c. 1055 – 1137), sometimes written as Gruffydd ap Cynan, 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, and was remembered as King of all Wales. As a descendant of Rhodri Mawr, Gruffudd ap Cynan was a senior member of the princely House of Aberffraw.