Ieuaf

Ieuaf (), perhaps a nickname representing Idwal ap Idwal (died 988) to distinguish him from his father Idwal Foel, was joint king of Gwynedd in northern Wales from 950 to 969 with his brother Iago ab Idwal. He possibly also ruled Powys for some time. Ieuaf was a son of King Idwal Foel (Idwal the Bald), who had become King of Gwynedd from 916 on the death of his father Anarawd ap Rhodri. Ieuaf's paternal great grandparents were Rhodri Mawr, King of Gwynedd and Angharad ferch Meurig of Ceredigion.

Upon his father Idwal's death in battle against the Anglo-Saxons in 942, he and his brother Iago ab Idwal were driven from their kingdom by their uncle Hywel Dda of Deheubarth, who took the crown for himself. On Hywel's death in 950, Ieuaf and Iago were able to drive out Hywel's sons, their cousins, at the Battle of Carno and reclaim the kingdom. However, fighting continued, with the brothers raiding as far south as Dyfed in 952 and their cousins raiding as far north as the Conwy valley in 954.

The southern princes were finally defeated at the Battle of Llanrwst and chased back to Ceredigion. Having won, the brothers then began to quarrel among themselves. Iago took Ieuaf prisoner in 969, and Ieuaf played no further role in Gwynedd. Some sources indicated Ieuaf was imprisoned, (historian John Edward Lloyd stated that Ieuaf remained in captivity until his death in 988), others that he was executed on his brother's orders.