Cadwallon ap Ieuaf (died 986) was a King of Gwynedd from 985 to 986.
Cadwallon was the son of Ieuaf and succeeded to the throne of Gwynedd on the death of his brother Hywel ap Ieuaf in 985. He only reigned for a year, for in 986 Maredudd ab Owain of Deheubarth invaded Gwynedd, slew Cadwallon and annexed his kingdom.[1]