Ólchobar (d. 851), son of Cináed, king of Cashel and abbot of Emly, belonged to Éoganacht Locha Léin. He became abbot of Emly in 825 on the death of Flann son of Fairchellach; he may have attained the kingship of Loch Léin (west Munster) in 833 in succession to his kinsman, Cobthach son of Máel-dúin.
In 847 Ólchobar was chosen as overking of Munster after the death of the powerful Fedelmid (qv) son of Crimthann, who belonged to the rival dynasty of Éoganacht Chaisil. He is the only west Munster ruler whom the Cashel regnal list admits without reserve. The fact that he was a cleric, and succeeded to the paramount kingship at a time when his lineage was losing its hold on west Munster, suggests that he was selected as a compromise candidate to minimise conflict between the Éoganacht dynasties. In alliance with the overking of Leinster, Lorcán son of Cellach, Ólchobar won a signal victory over the vikings at the north Leinster location of Sciath Nechtain in 848, the same year in which the king of Tara, Máel-Sechnaill (qv) son of Máel-ruanaid, likewise crushed a viking force.
After these victories a legation was dispatched to the court of the emperor Charles the Bald by a certain rex Scottorum, as noted by the Frankish ‘Annales Bertiniani’. The Irish king has been tentatively identified as Ólchobar, rather than the king of Tara, in view of the Leinster connections of Sedulius Scottus (qv), who apparently was included in the delegation. Ólchobar died in 851. His successors in the kingship of Cashel were the brothers Áilgenán and Máel-guaile (d. 859), sons of Donngal.