Ér, Orba, Ferón and Fergna, sons of Éber Finn, were, according to medieval Irish legends and historical traditions, joint High Kings of Ireland for half a year after they killed their cousins Luigne and Laigne, sons of Érimón, in the Battle of Árd Ladrann.
Ér, Orba, Ferón and Fergna, sons of Éber Finn, became High Kings of Ireland for six months following their killing of their cousins Luigne and Laigne, sons of Érimón, in the Battle of Árd Ladrann, as depicted in medieval Irish legends and historical accounts.