Morgan ab Owain (died 1158) was a Welsh king and Lord of Caerleon. He was a son of Owain Wan and thus a grandson of Caradog ap Gruffydd, the last Welsh king of Gwent. After Caradog ap Gruffydd was killed in 1081 in the Battle of Mynydd Carn against Rhys ap Tewdwr, his son Owain Wan ruled only over Gwynllŵg. Most of Gwent was conquered by the Anglo-Norman lord Robert Fitzhamon in the following years.