The most numerous name in Ireland, Murphy is derived from Ó Murchada or Ó Murchu, meaning sea warrior. There are several septs, or clans, of Murphys. The most famous Murphy was Dermot MacMurrough, who invited the Normans to Ireland in the 12th century. The present chief of the name is David O'Morchoe, a farmer in Co. Wexford. The Irish version of Murphy was first anglicised to O'Morchoe, in the 16th century, and David O'Morchoe's grandfather changed his name to this version by deed poll in 1895.

The achievements of the Murphy clan are numerous and wide ranging. Patrick Murphy, born in Co. Down in 1832, was the tallest man in Europe, standing at 8 ft. 1in. Another Murphy of repute was William Martin Murphy. He founded the Irish Independent  newspaper in 1905, and was also the head of the company that ran the Dublin tramway system. He became notorious as the employers' leader in the great Dublin lockout of 1913.