- "I used to do what you do."
- ―James Marrick[src]
James Marrick was a former CIA Black Ops and a member of the International Oversight Advisory who was tasked to watch over Stargate Command due to the fact Richard Woolsey's time was being taken up by the Atlantis expedition.
He was first seen interrogating Tomin about his time as a Commander of the Ori Army. After this he joined SG-1 on their mission to the Alteran Home Galaxy to find the Ark of Truth. While SG-1 was on Celestis searching for the Ark, he turned on and accessed the Asgard computer core of the Odyssey. It was later discovered when Lt. Colonel Cameron Mitchell and Lt. Colonel Samantha Carter returned to the ship that he was constructing a Replicator using the core, the IOA having concluded that the best way to destroy the Ori after the SGC had refused to destroy the Supergate was to unleash the Replicators upon their forces. Carter sent Mitchell to get an Anti-Replicator gun but when she deactivated the shield around it and blasted it, the ARG had no effect; the new Replicators had been redesigned to be immune to ARGs and could only be shut down by an initially-unspecified command code. While they searched for the Replicator, Marrick was confined to the ship's brig for his actions. After the Replicators started to replicate and grow in numbers, they eventually found Marrick and broke into his cell.
He was trapped so they easily attacked him and seemingly took over his body, with what seemed to be an entire Replicator having burrowed into his body to control his central nervous system and find out for themselves the built-in self-destruct activator that the IOA had built in so they could deactivate it. He eventually moved to be near the Replicator queen and began fighting Mitchell when he located the Queen in order to plant C-4 to destroy it. In spite of Mitchell's combat training the Replicator enhanced Marrick proved much stronger and impervious to pain, even being shot in the chest failed to stop him. He beat Mitchell severely and leaving him bleeding in several places. Marrick briefly managed to regain control of himself when Mitchell pulled out one of the Replicator's legs, which was stuck into the back of Marrick's head. Marrick was able to tell Mitchell where the self-destruct was - on the back of the data crystal he used to create them.
Once the Replicator regained control Marrick brutally beat Mitchell before Mitchell managed to impale Marrick on an electrical conduit. This bought Mitchell enough time to get to his detonator to set off his explosives. The resulting explosion destroyed the Queen and disintegrated Marrick's body, putting him out of his misery. However, the Replicator blocks of the Replicator inside Marrick reformed into the shape of a human skeleton and began to move back at Mitchell, possibly intending to kill him again until, at the last second Carter inputted the self-destruct, destroying all the Replicators including the skeleton version on board the Odyssey. (SG1: "The Ark of Truth")
Snide and arrogant, Marrick was extremely manipulative and willing to go against the wishes of SG-1 and the SGC to create a Replicator that would be capable of infecting the Ori ships, even at the cost of destroying the Odyssey itself and those on board the ship.
Upon being infected with the Replicator nodes he had knowingly created, Marrick became an emotionless, unfeeling machine and also the Replicator's lone puppet as they attempted to stop the IOA's plan from working. He was also shown to unaffected by any regular punches or attacks Mitchell inflicted on him yet Merrick was capable of causing Mitchell much damage.
- Is the first IOA representative to have become possessed or taken over by an enemy of the Tau'ri and is also the first member of the IOA to have been killed in the line of duty.