Weyoun was a Vorta diplomat and leader in the service of the Dominion during the late 24th century. Like all Vorta, he was a clone; at least eight copies (five of which were encountered by the Federation) were known to exist. Weyoun became a well-known Vorta in the Alpha Quadrant during the Dominion War, serving as the Dominion representative to the Cardassian Union. In this capacity, he personally oversaw most aspects of the war, although his presence was largely to ensure the loyalty of Cardassian leaders such as Gul Dukat, Legate Damar, and Legate Broca.
The war brought Weyoun into contact with many leaders from the Alpha Quadrant. He visited Deep Space 9 to negotiate with Benjamin Sisko when the cold war between the powers of the Alpha Quadrant and the Dominion showed signs of eroding into open hostilities. Shortly thereafter, he returned with a fleet of Cardassian and Dominion warships to take control of the station, and went on to serve as the Dominion overseer of the station during the brief occupation that followed. In this capacity, he personally negotiated a nonaggression pact with Bajor and dealt with representatives from such powers as the Romulan Star Empire, Breen Confederacy, and Tholian Assembly. Until his death, he remained the only "Solid" that the Female Changeling claimed that she had ever trusted.