Marshall Sumner

"He carried the burden of a leader, and he carried it well."

- John Sheppard

Marshall Sumner was the first leader of the Atlantis Expedition's military contingent. He objected to John Sheppard's inclusion into the team, stating that he disliked any officer who failed to follow the proper chain of command.

After Atlantis was discovered to be underwater and slowly flooding, Sumner led the reconnaissance team that made first contact with the Athosians. Though he allowed Sheppard to attempt to establish a rapport with them, he paid less attention to the people than to any potential technology or suitable evacuation site that might be found; this led him to disregard the Athosians' warning against exploring the ruins of an Ancient city there. Teyla Emmagan observed that Sumner "looks through me as if I were not there."

When the Wraith culled the Athosians, Sumner was captured along with some of the Athosians. When the Wraith came to collect an Athosian prisoner, Sumner attempted to offer himself to save the Athosian, but the Wraith refused the initial offer. After killing the Athosian, they returned to the cell and brought Sumner before the Wraith Keeper, who attempted to interrogate him about Earth. He refused to tell her the Stargate address, and, noting his surprising strength of will, the Keeper fed upon him, commenting that she had not tasted such strength in a very long time. Although Sheppard tried to rescue him, he did not arrive until Sumner appeared to have aged by several decades, with the Keeper still feeding on him. When the Keeper proved resistant to gunfire, Sheppard shot Sumner instead, believing it was what Sumner wanted him to do.

Sumner's death would be a major source of contention between Sheppard and both Dillon Everett, who had considered Sumner a very good friend, and Steven Caldwell. , although both eventually acknowledged that he had done so for the right reasons. For his part, Sheppard spoke highly of Sumner in a message back to Earth, saying he had borne the burden of a leader well and that in light of the looming Wraith assault, he wished Sumner was still with them.