Ensign Murphy was Starfleet security officer serving aboard the USS Voyager under Captain Kathryn Janeway. Murphy was stranded in the Delta Quadrant when the Voyager was forcibly brought there by the Caretaker in 2371.
Murphy was among the Starfleet officers who took part in Tom Paris' Paris Radiogenic Sweepstakes bets on the holodeck at Chez Sandrine. (VOY: "Meld")
He was part of Tuvok's security team which entered main engineering after Neelix defeated Michael Jonas. (VOY: "Investigations")
In 2372, he was with the crew of the Voyager marooned on Hanon IV and among the crewmembers who were attacked by the natives. (VOY: "Basics, Part I", "Basics, Part II")
Murphy had dinner in the mess hall when Neelix served his new juice to Tuvok. (VOY: "Flashback")
In 2373, Murphy was ordered by Chakotay, to escort the Ferengi Arridor and Kol to secured quarters. The Ferengi, however, were able to knock Murphy unconscious and were able to escape, leaving Murphy with a concussion. (VOY: "False Profits")
Murphy served as relief tactical officer during the absence of Tuvok. (VOY: "Rise")
Murphy was played by regular background actor Shepard Ross, who received no credit for his appearances.