Popular Irish surnames include Brennan, Brown, Boyle, Callaghan and Campbell. Ireland was one of the first countries to use hereditary surname. Families added prefixes to a surname to designate son or grandson. For example, the prefix "Mac" means "son," while the prefix "O" signifies "grandson." The prefixes established paternal lineage.
There are dozens of common Irish surnames, including the surname Clarke, which originated from O Clery, one of the oldest Irish surnames. Clarke is most common in the Cavan region. Immigrants often anglicized original Irish surnames to Byrne, Connor, Daly, Doherty and Doyle. Other names given an Anglican slant include Dunne, Flynn, Lynch and Quinn. Ryan and White are others anglicized from their original Gaelic spellings.
The surname Connor originated from the Irish name ? Conchobhair, which means "champion" and "hero." The name is one of three royal Irish families from the Clare, Galway, Kerry Offaly and Ulster provinces, among others.
Cassidy, Conroy, Cooney, MacCormick and Dempsey are more Irish surnames. Delaney, Dwyer, MacFadden, Fanning and Fitzpatrick are others. Flood, O Grady, Lawless, Kennedy and MacMahon are other popular surnames among the Irish. Many Irish surnames are adaptations with Scottish, Welsh and English origins stemming from historical invasions and attempted colonization. Butler, Burk and Barry are Irish surnames with Norman influences.