Toirdelbach Mor O'brien
Toirdelbach Mor was born in 1009.  He died at the age of 77 on July 14th, 1086.

 Murchadh O'brien King Of Ireland
Murchadh was born in 1046.  He died at the age of 73 in 1119.

 Diarmait Mactoirdelbach O'brien
Diarmait Mactoirdelbach was born in 1060 in Munster, Ireland.  He died at the age of 58 in 1118.