Seán O'Donnell
Seán O'Donnell was the son of Conchobar O'Donnell, king of Tyrconnell killed in 1342. After Aonghus was slain in 1352, Seán fought their uncle Feidhlimidh, who had taken the kingship; Feidhlimidh and his son were probably captured in 1356 and killed the next year.
Seán ruled until 1359, when Cathal Óg O'Connor of Sligo seized power, returning when Cathal died in 1362. He and his son were killed at Assaroe monastery in 1380.