United States military sergeant assigned as a Stargate technician in the Stargate Command control room when SG-1, pinned down by Jaffa on P2X-887, dialed Earth. Missing in action, O'Brien feared their iris code had been compromised, and transmitted a "hold" command back through to their G.D.O.s until he could receive further instructions from General Jack O'Neill.
O'Neill went against protocol and ordered O'Brien to open the iris, ushering SG-1 back to Earth.
Zero Hour - O'Brien is on-duty in Stargate Command's control room when SG-1, believed to be captured by Baal, suddenly dials Earth.
200 - O'Brien appears as a zombie in a story imagined by Cameron Mitchell.