Major John Sheppard of the US Air Force was a member of the first expedition to Atlantis under the command of Dr. Elizabeth Weir, and he became the senior military officer for the Atlantis mission. He commands the flagship off-world team in Atlantis, which includes Dr. Rodney McKay. When members of SG-1 arrived in Atlantis to carry out a joint mission that would establish a wormhole from the Pegasus Galaxy to block the Ori supergate in the Milky Way, Lieutenant Colonel Sheppard participated in the initial briefing but was not a part of the mission. He did, however, offer Mitchell some friendly advice for managing Rodney McKay. McKay, who would join the SG-1 mission, is mortally allergic to citrus, and Sheppard recommended that Mitchell keep a lemon available as a threat to secure McKay's cooperation when he insisted that the mission would fail.
Portrayed by: Joe Flanigan
Episode Reference: The Pegasus Project