Adrian Conrad was a wealthy industrialist and the head of Zetatron Industries, a multinational corporation based in Seattle. He had been in the late stages of Burchardt's Syndrome, an extremely rare condition with no known cure that affects the immune system, leaving the body vulnerable to a host of diseases. Through unknown sources, he and his assistant, Diana Mendez, arranged to procure a symbiote from one of Cronus's Jaffa who had been captured alive during the second mission of the Russian stargate program and taken by a renegade faction of Russian military intelligence. He also kidnapped Carter because of her experience as a former host, with the intention of implanting himself with the symbiote for a cure, and using tests on Carter to determine a safe means for its removal. In the deserted St. Christina's Hospital in the suburbs of Seattle, immunologist Dr. Neil Brooke oversaw the implantation procedure. The procedure was successful, however, before the symbiote could be removed, Conrad escaped, killed Diana, and was taken into custody by Colonel Simmons of the NID.
Prior to the implantation, the symbiote had been cloned by scientists at Conrad's subsidiary, Immunitech Research, in order to create a kind of super-drug. However, in a lab accident, many immature cloned symbiotes took hosts among the townspeople of Steveston, Oregon, creating "nightwalkers" who were closely monitored by the NID as they became active each night and labored to construct a spacecraft in which to escape Earth.
Meanwhile, Conrad was being held by Simmons at a secret NID safe house in Minot, North Dakota in a deal for the exchange of information. O'Neill and Maybourne launched an investigation and traced Conrad to the safe house where they forced him to cooperate. The Goa'uld's knowledge provided a solution to rescue Teal'c when he was trapped within the stargate matrix, and also provided incriminating evidence against Colonel Simmons. Both Conrad and Simmons were arrested and imprisoned by the government, but when rogue NID operatives commandeered the Prometheus, the hijackers demanded their release. On board the Prometheus, the Goa'uld within Conrad provided the information to repair the hyperdrive and to direct the ship to its destination. However, in a struggle with Simmons, Conrad was shot and killed, and the symbiote entered Simmons instead. Simmons struggled with O'Neill and Teal'c, and he too was killed when he was sucked out the airlock door of the ship.
Portrayed by: Bill Marchant