Founding commanding officer of SG-1. Joining the Air Force at 18, O'Neill proved himself to be an exceptional and gifted airman and was later assigned to a Special Forces unit. He resigned from the military when his son, Charlie, died by accidentally shooting himself with O'Neill's service weapon. O'Neill was devastated by the loss, which eventually drove his wife to divorce him. He was later recalled to duty by his former commanding officer and sent through the Earth's first discovered Stargate, in a mission that gave him a new desire to live. After several years of leading SG-1 through missions across the galaxy, helping to save Earth innumerable times, he was promoted to Brigadier General and chief of Stargate Command.

107, The Nox -- Died, shot by Apophis' jaffa; Revived by the Nox.

207, Message in a Bottle -- Critically injured, punctured through the shoulder by an armature from an alien orb.