Ó Raghailligh
Ó RAGHAILLIGH, Ó RAGHALLAIGH—I—O Reyly, O Riellie, O Realy, O Reely, O'Reilly, O'Reiley, O'Rielly, O'Realley, Reilly, Rielly, Really, Realy, Reely, Riley, &c.; 'descendant of Raghallach'; also pronounced Ó Rághallaigh, Ó Raighilligh, Ó Raoghallaigh, &c., and sometimes shortened to Ó Raghaill, &c., which see. The O'Reillys, who are the same stock as the O'Rourkes, were chiefs of Breifney-O'Reilly, which originally comprised the greater part of the present Co. Cavan. In the course of the 13th and 14th centuries they became very powerful and extended their dominion over the whole Co. Cavan and parts of Meath and Westmeath; and they were sometimes chiefs of all Breifney. They maintained their independence as a clan down to the time of James I, and continued in possession of considerable property until the Cromwellian confiscations. Many of the O'Reillys attained to high ecclesiastical rank, no fewer than five of the name having been Primates of Armagh. The name is now one of the most common in Ireland, but owing to its numerous dialectical variations is variously anglicised in different parts of the country.
Alphabetical Index to Irish Surnames