spear carrier
n.— «They are “Spear Carriers” which in movie parlance, is the expendable personel who always buy the farm in the battle scenes. I know a couple stunt guys and extras who have made their careers out of being able to die well on the silver screen.» —“Re: Hello to all.please read my post and give your answers” by Gunner Asch Usenet: rec.crafts.metalworking July 30, 2007. (source: Double-Tongued Dictionary)
“red shirt” is a synonym for “spear carrier”. Its meaning comes from the old Star Trek series. If Captain Kirk and Spock transported down to a planet with a couple of red shirts, you could be sure that only Kirk and Spock would come back alive.