Fergus mac Fothaid
He was of the Síl Cathail sept and grandson of Dub-Indrecht mac Cathail (died 768), a previous king. The Síl Muiredaig sept had dominated the kingship from 796-839 but this was broken by the predecessor of Fergus, his second cousin Murchad mac Áedo (died 840).
Nothing is known of his short reign other than his death notice in the annals.
- Byrne, Table 20; Ó Corráin, pg.178
- Annals of Ulster, AU 843.6