The Delbna or Delbhna was a Gaelic Irish tribe in Ireland, claiming kinship with the Dál gCais, through descent from Dealbhna son of Cas. Originally one large population, they had a number of branches in Connacht, Meath, and Munster in Ireland.
According to their earliest legends, the Delbhna took their name from their ancestor Delbáeth, son of either Aengus or Ogma, a god of the Tuatha Dé Danann who succeeded The Dagda, or Eochaid Ollathair, as High King of Ireland and who for various reasons is identified as the same as Tuireann. A later story told that the Delbhna descend from Suman, son of Lugh Delbáeth, son of Cas, progenitor of the Dal gCais.