Murphy is an Irish surname meaning "Sea Warrior." Origins and variants. The surname is a variant 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). According to historian C. https://en.wikipedia.org/wiki/Murphy