Murphy is an Anglicized version of two Irish surnames: Ó Murchadha/Ó Murchadh ("descendant of Murchadh"), and Mac Murchaidh/Mac Murchadh ("son of Murchadh") derived from the Irish personal name Murchadh, which meant "sea-warrior" or "sea-battler". (Muir meaning "sea" and cath meaning "battle").
In modern Irish, "Ó Murchú", rather than "Ó Murchadha", is used.
Murphy is the most common surname in Ireland, the fourteenth most common surname in Northern Ireland and the fifty-eighth most common surname in the United States.
By Dean Hanley