Muireadhach mac Aedh, Lord of Clann Cosgraigh, died 1124.
He was a distant cousin of the Muintir Murchada, of whom the O'Flahertys were chiefs.
[2] John O'Donovan, who edited the 1856 publishing of the Annals of the Four Masters, inserts "O'Flaithbheartaigh" after Ruaidhri's name, but this appears to be a mistake; O'Donovan confuses the Lord of Clann Cosgraigh with another Muireadhach mac Aedh mac Ruaidhri, who was an actual O'Flaherty.
[3] Muireadhach's immediate descendants adopted the surname Mac Aedha.
The surname is now rendered McHugh or Hughes, less commonly McGagh (better reflecting the Irish pronunciation).