David blue as Eli Wallace– Named Eli Hitchcock in the casting call, Eli Wallace is a "total slacker" in his early twenties and an "utter genius" in mathematics, computers and other fields. He is a social outcast with an "acerbic sense of humor", and lacks confidence in his intelligence.
Brian J. Smith as Matthew Scott[1] – A skilled and well-trained Junior SGC member in his early twenties holding the rank of Lieutenant. He is "mentally unprepared for the urgency of the situation" aboard the ship. He was named Jared Nash in the initial casting call.[20] Before being cast, Brian J. Smith had been working as a stage actor in New York for a year and a half and had seen a couple of Stargate episodes. Smith taped his Stargate Universe audition and was invited to a screen test in Los Angeles. He received the news of being cast a few days after the screen test.[26]
Jamil Walker Smith as Ronald Greer[1] – In early casting documents named Ron "Psycho" Stasiak,[20] Ronald Greer is a "big, strong, silent" marine aged 20 with a mysterious past who lacks control over his temper in non-combat situations. The character breakdown compares him to Eric Bana's character "Hoot" in Black Hawk Down.[20] His rank is Sergeant.[1]
Robert Carlyle as Dr. Nicholas Rush[1] – The "ship's brilliant Machiavellian scientist"[27] whom Joseph Mallozzi had first mentioned in his blog in mid-November 2008 as Dr. David Rush.[13] Rush is the only character who was not included in the initial casting character breakdowns,[20] but Brad Wright confirmed Carlyle as a series regular (instead of recurring) in early January 2009.[14] Mallozzi rectified casting reports in mid-December 2008[28] that Rush "is not the leader of the unplanned expedition. That honor falls to Colonel Everett Young. For now. But things could have a way of changing on board a ship manned by a disparate group with very different agendas...".[27] According to Robert C. Cooper, Carlyle will keep his Scottish accent for the role.[29]
