Gael.
Murchadh "sea-warrior." The Celtic "sea" element is also in names
Muriel (q.v.),
Murdoch (O.Ir.
Muireadhach, O.Welsh
Mordoc "mariner"), etc.
Murphy bed (1925) is named for U.S. inventor William Lawrence
Murphy (1876-1959).
Murphy's law first attested 1958, used of various pessimistic aphorisms. If there ever was a real
Murphy his identity is lost to history. Said to be military originally, and probably pre-dates the earliest printed example (the 1958 citation calls it "an old military maxim").