Peter DeLouise is an Major in the United States Air Force, and was a senior member of the crew assigned to the newly commissioned battlecruiser Prometheus. DeLouise occupied the pilot's station during Prometheus maiden flight, which was originally to have taken the ship to P7X-009, and when damage to the ship's hyperdrive forced it to relocate instead to P3X-744. When this second jump caused an overload in the ship's hyperdrive core, DeLouise piloted the ship away from the explosion, and subsequently detected the first signs that the planet below was inhabited — a pair of ballistic missiles launched at the ship. Unable to maneuver, he monitored the missiles' approach until they self-destructed, after Colonel Jack O'Neill had successfully made contact with the Tagreans.
After the Tagrean Stargate had been located by a search team led by Teal'c and Jonas Quinn, both of whom were subsequently captured by forces under the command of Kalfas, DeLouise piloted the Prometheus to the site as part of O'Neill's plan to resolve the situation. (SG1: "Memento")
DeLouise's name is never spoken on screen, and he is credited only as "Navigator," but the name ("Peter DeLuise" without "o") was printed on his uniform. This may have been an homage to Peter DeLuise, who directed "Memento" as well as many other episodes. Ray Galletti clarified that it was Peter DeLuise's idea to name the character after himself. DeLouise surname (with "o") is mentioned only on IMDb.