Conaire Mór (the great), son of Eterscél, was, according to medieval Irish legend and historical tradition, a High King of Ireland.
In the Old Irish saga Togail Bruidne Dá Derga he is conceived when his mother is visited by Nemglan who flies in her skylight in the form of a bird, and is brought up as Eterscél's son.
According to the Lebor Gabála Érenn, he took power after killing his predecessor, and his father's killer, Nuadu Necht.
A bull is killed, a man eats his fill of its meat and drinks its broth, and sleeps as incantations are chanted over him.
The leader of the bird troop is called Nemglan and he tells Conaire to go naked to Tara, where he will be made king, and places several geasa (taboos) on his reign.
His three foster-brothers, the three sons of Dond Désa, whom Conaire had exiled to Alba (Britain) for their crimes, had made alliance with the king of the Britons, Ingcél Cáech, and they were marauding across Ireland with a large band of followers.
Mac Cécht travels across Ireland with Conaire's cup, but none of the rivers will give him water.
Conaire's severed head drinks the water and recites a poem praising Mac Cécht.
The Lebor Gabála Érenn synchronises his reign with that of the Roman emperor Augustus (27 BC – AD 14), and after the birth of Christ, and makes him contemporary with legendary provincial kings Conchobar mac Nessa, Cairbre Nia Fer and Ailill mac Máta.