Ernaine mac Fiachnai (died 636) was a King of Ailech and head of the Cenél nEógain branch of the northern Uí Néill.
He was the brother of the high king of Ireland Suibne Menn (died 628).
In 630 these two branches of the family clashed at the Battle of Leitheirbe and Ernaine was victorious over Máel Fithrich mac Áedo, who was slain, of the Cenél maic Ercae.
[3] The Cenél Feradaig branch then dominated the kingship for most of the 7th century.
This biography of a member of an Irish royal house is a stub.