|Author||Rev Patrick Woulfe|
|Source||Irish Names and Surnames|
Ó BIRN—O Birn, O Birne, O Byrn, O'Beirne, O'Bierne, O'Byrne, Birne, Beirne, Byrne, Birnes, Byrns, Byrnes, (Byron, Burns); 'descendant of Biorn' (the Norse personal name Bjorn); a variant of Ó Beirn, which see. The present is the usual form of the name in the Annals; Ó Beirn was apparently more common at a later period. There are two distinct families of the name in Connacht: (1) Ó Birn of Siol-Muireadhaig. This family first came into prominence as stewards to the O'Connors, Kings of Connacht and sometimes of all Ireland. About the middle of the 13th century, they superseded the O'Monaghans as chiefs of Tir-Bhriuin, a beautiful district in Co. Roscommon, a position which they continued to hold for more than three hundred years. In the year 1570, Teig Byrne, alias O Byrne, was 'the chiefest of Tirowyne' (Tir-Bhriuin), and several gentlemen of the name are mentioned in the Fiants of Elizabeth. (2) Ó Birn of Ui Fiachrach. This family enjoyed, at the beginning of the 15th century, a considerable estate in Co. Mayo, a little to the north of Ballinrobe, and there were respectable families of the name in that county at the end of the 16th century. O'Donovan found the name, under the anglicised form of Byrne, in the very district anciently occupied by the family. O'Beirne and O'Byrne were in use in Lecale, Co. Down, at the beginning of the 17th century, but whether the Irish was Ó Birn, or Ó Broin (which see), I am unable to say.
Alphabetical Index to Irish Surnames