Fiachnae mac Áedo Róin

Fiachnae mac Áedo Róin (died 789) was a Dál Fiatach ruler of the over-kingdom of Ulaid in Ireland. He reigned from 750 to 789. He was the son of Áed Róin (died 735) and brother of Bressal mac Áedo Róin (died 750), previous kings. This family had their base in modern-day County Down, Northern Ireland.