O'BEIRNE Family History
Recorded in the spellings of O'Beirne and Beirne, this is an Irish surname. It is claimed by eminent authorities that although it is pronounced exactly the same as more familiar O'Byrne, the two clans are totally separate. O'Beirne being originally from County Roscommon and O'Byrne from County Kildare, although for the past eight hundred years South Wicklow has been their home. This may be so but it would take some proving. What is certain is that the O'Beirnes have long been associated with the clan MacDermot, and in the 13th century they combined to drive the O'Monahans out of the territory known as Tir Bruin, near Jamestown, on the Roscommon side of the Shannon.