Cadwallon Cadwallon (role-playing game) Cadwallon Lawhir ap Einion Cadwallon ab Ieuaf Cadwallon ab Owain Cadwallon ap Cadfan Cadwallon ap Madog Cassivellaunus Cathal Catuvellauni Common Brittonic Cædwalla Gruffudd ap Cynan Hertfordshire Late Iron Age Proto-Celtic Welsh language