1 Son of Áed (1), son of Ainmire, and a historical ard rí [high king] of Ireland (c.628–42) who plays a leading role in the Cycle of Kings, most notably Buile Shuibhne [The Frenzy of Sweeney]. Domnall first became ard rí when his predecessor, Suibne Menn, was killed by Congal Cáech of Ulster. Congal also opposed Domnall but was defeated at Dún Cethern, whereupon he fled to Scotland. There he enlisted the aid of Domnall Brecc, the king of Dál Riada, the Irish kingdom in Argyllshire (since 1974, north Strathclyde), which at that time included some territory in north-eastern Ireland. Spurred on by Congal, Domnall Brecc invaded Ireland with a large army but was defeated by the Irish king Domnall at the Battle of Mag Rath (Moira), 637. One political result of Mag Rath appears to be Dál Riada's loss of Irish territories. The battle also causes the madness of Suibne in Buile Shuibhne.
Because of the curse put upon Tara by the (fanciful) St Rúadán, Domnall moved his seat to Dún na nGéd on the banks of the Boyne. According to Fled Dúin na nGéd [Feast of Dún na nGéd], two terrifying spectres, male and female, appeared before a feast, devoured all the food provided for the assembly, and then vanished. The malignant milieu they left also helped to contribute to the Battle of Mag Rath and the madness of Suibne.
The text of Fled Dúin na nGéd was edited by John O'Donovan (Dublin, 1848), by Carl Marstrander in the Norwegian journal Videnskabs-Selskabets Skrifter, 2/6 (1909), and by Ruth Lehmann (Dublin, 1964).
2 King of Decies in Cath Gabhra [The Battle of Gabhair/Gowra]. His son wanted to marry Sgiamh Sholais, the daughter of Cairbre Lifechair. He was killed by Fiachra, a son of Fionn mac Cumhaill.