Nigel O'Conner was a human male soldier in the Systems Alliance military. He was born on the human homeworld and capital planet known as Earth among the various species of the Galaxy. He graduated basic training alongside Johun Shepard, who would later become a war hero and a Spectre, the elite agents of the interstellar government known as the Citadel Council. After completing basic training, the Irish soldier was assigned to the SSV Midway alongside Johun Shepard. He was taught how to drive the Mako, a Systems Alliance light tank and rover used for planetary surface exploration, alongside Johun Shepard, on the remote, desert world of Edolus by Gunnery Chief Daniel Arbor.