In Irish mythology Delbáeth or Delbáed (modern spelling: Dealbhaoth or Dealbhaodh), possibly meaning "fire shape(d)", was the son of either Aengus or Ogma of the Tuatha Dé Danann, and Ethniu of the Fomorians. He succeeded his grandfather Eochaid Ollathair, a.k.a. the Dagda, as High King of Ireland. He was the father, by Ernmas, of the three eponymous Irish goddesses Ériu, Banba and Fodla. He ruled for ten years, before dying at the hand of his son, Fiacha.
Certain portions of Lebor Gabála Érenn identify Delbáeth as the father of Brian, Iuchar and Iucharba, mentioning that Delbáeth has another name Tuirill Biccreo. For this reason Delbáeth is identified as the same character as Tuireann.
Delbáeth is also given as a name of Lugaid mac Tail after Lugaid lights an enchanted fire from which burst five streams.
The Delbhna, a people of early Ireland, claimed descent from him.
Another Delbáeth, Delbáeth Mac Neit, is identified in the same section of Lebor Gabála Érenn as Tuirill Biccreo's great-grandfather.