Cathair Mór ("the great"), son of Feidhlimidh Fiorurghlas, a descendant of Conchobar Abradruad, was, according to Lebor Gabála Érenn, a High King of Ireland.
[3] Cathair ruled for three years, at the end of which he was killed by the Luaigne of Tara, led by Conn Cétchathach.
The chronology of Geoffrey Keating's Foras Feasa ar Éirinn dates his reign to 113–116, that of the Annals of the Four Masters to 119–122.
Cathair's daughter Eithne Tháebfhota is fostered by a hospitable Leinsterman named Buchet who has many herds of cattle, but Cathair's sons so exploit Buchet's hospitality that he is left with only one bull and seven cows, and the king, now old and enfeebled, is unable to restrain them.
Buchet and his family, including Eithne, are reduced to living in a hut in the forest in Kells, County Meath.