Eóganacht Glendamnach were a branch of the Eóganachta, the ruling dynasty of Munster during the 5th-10th centuries. They took their name from Glendamnach (Glanworth, County Cork). They were descended from Óengus mac Nad Froích (died 489), the first Christian King of Munster through his son Eochaid mac Óengusa (died 522) and grandson Crimthann Srem mac Echado (died c. 542). Kings of Cashel and Munster from the Eóganacht Glendamnach were:
King lists for the 6th century give a virtual monopoly to the Glendamnach branch, but those based on the Laud Synchronisms were probably written at Cloyne in the mid 8th century, a monastery favorable to the Glendamnach branch. The Eóganacht Glendanmach were considered part of the inner circle of Eoganachta dynasties which included the Chaisil and Áine. These three branches rotated the kingship of Munster in the 7th and much of the 8th centuries. The last king from this branch died in 821. Their later ruling sept were the Ó Caiomh (O'Keeffes).