Question: what is the most common last name in ireland
Answer: # Surname Modern Irish Original Irish Meaning Murphy Ó Murchú Ó Murchadha Mac Murchaidh Descendant of Murchadh ( a personal name meaning `` Sea hound / warrior '' ) ( O ' ) Kelly Ó Ceallaigh Descendant of Ceallach ( `` strife '' ) ( O ' ) Sullivan Ó Súilleabháin Descendant of Súilleabhán ( `` dark - eyed one '' , `` one - eyed '' or `` hawk - eyed '' ) Walsh Breathnach Breatnach `` Breton '' , `` Welshman '' 5 Smith Mac Gabhann Son of a smith 6 O'Brien Ó Briain Descendant of Brian 7 ( O ' ) Byrne Ó Broin Descendant of Bran 8 ( O ' ) Ryan Ó Riain Ó Riain Ó Mao