CONAIRE MOR

In Irish mythology, 'Conaire Mor' was a High King of Ireland, the son of king Eochaid Airem and his daughter, the king having been fooled by the magical powers of Midir (see also). As he chose to ignore the various geasa placed upon him at the moment of his birth, he found his death.
The broken geas that led Conaire to his doom was the warning not to go to Da Derga's Hostel; having also been warned about the way to the hostel, he met there three men dressed in red and riding red horses, that were indeed messengers announcing his death, but he ignored them. Once he arrived at the hostel, where his enemies were, they attacked him and his men and Conaire and many of his warriors were slain.
The sons of Conaire, Cairpre Músc, Cairpre Baschaín and Cairpre Riata were claimed as eponymous or mythical founders by the Múscraige, the Corco Baiscind (both of the Déisi Tuisceart), and by the Dál Riata respectively, as well as by the Corco Duibne of Munster.