Ó hEachthigheirn, Ó hEachthigherna, Ó hEichthigheirn, Ó hEachthighearna, Ó hEachiairn.
Ó hEachthighearna: “lord of the horse”.
Ahern(e), Ahearn(e), Hearn(e), O’Hearn(e).
The family are said to be descended from Echtigern who was a brother of the High King of Ireland, Brian Boru. Being of the Dalcassians, they were an important sept in the area between Limerick and Sixmilebridge in County Clare, east of the Owenogarney River which flows past Bunratty Castle.
In 1151, five chieftains of the family were killed in battle at Móin Mhór near Mourne Abbey. They were mostly driven out of the area by the MacNamaras around 1318, and appeared again in concentrated force in East Cork during the 16th century.
You can find out a lot more at the official Ahern clan website.