Robert Makepeace

The long-time commander of Stargate Command's SG-3 Marine unit, Colonel Makepeace would not be considered the friendliest member of the S.G.C. But when it came to getting a job done, the tough and to-the-point Marine completed his missions with a high success rate. For three years he served as the third-highest ranking officer on the base, beneath Colonel Jack O'Neill and General George Hammond. With help from the Asgard, Makepeace was discovered to be a spy for the rogue N.I.D. group under the command of Colonel Harold Maybourne, who was covertly reverse-engineering stolen alien technologies. Smaller items stolen by the rogue group would be left on a designated world for Makepeace to covertly pick up and pack back to Earth in his gear during routine missions.

O'Neill had Makepeace arrested and charged with high treason against the United States and its allies. He is presumably serving a prison sentence.