Omoc was one of the wisest among the Tollan.
He had learned well from the mistakes the Tollan had made with Sarita, a neighboring planet that destroyed itself after the Tollan shared their advanced technology with them. When his people were forced to evacuate their doomed planet, Omoc and his team were rescued by SG-1 after they failed to make it out in time.
Omoc largely refused to interact with members of Stargate Command, coming off as a sternly cold and humorless man, believing them to be too primitive. He was thus extremely resistant to forming an alliance with Earth, whom he believed only wanted to acquire the Tollan's superior technology. In the end, however, he developed a respect for Dr. Daniel Jackson and the rest of the team, who were eager to help the refugees escape the clutches of the NID's Colonel Harold Maybourne by contacting the Nox. Lya traveled to Earth to offer the Tollan sanctuary. (SG1: "Enigma")
Omoc and the others were eventually able to leave Gaia and reunited with their people on the new Tollan homeworld, Tollana. He became a member of the Tollan Curia, the civilization's leading governmental body. But when the Curia capitulated to the Goa'uld Anubis, who was poised to destroy them, Omoc was incensed. He urged them to fight, and was murdered by the Curia as part of a cover up. Before he was killed however, without giving the specific details he gave Narim a warning that Earth was in danger.
After his death, SG-1 attended his funeral which in his testament, or will, he had asked that only people he respected attend, with Narim noting that he had held a deep reverence for SG-1. His warning prompted Narim to start investigating his death, and ultimately saved Earth and potentially many other worlds from the phase-shifting weapons the Curia were building for the Goa'uld. (SG1: "Between Two Fires")