- See Martok, son of Urthog for the real Martok.
In late 2371, the real General Martok was captured while hunting sabre bear on Kang's Summit by the Dominion. The real Martok was taken to Internment Camp 371. The Martok Changeling assumed Martok's form and took his position as Chancellor Gowron's chief of staff. (DS9 episodes: "The Way of the Warrior", "In Purgatory's Shadow", "By Inferno's Light")
The Martok Changeling then worked to weaken the Klingon Empire and the United Federation of Planets to make the Alpha Quadrant ripe for Dominion conquest. In 2372, he convinced Gowron and the Klingon High Council that the Cardassian Detapa Council had been replaced by Founders. The Klingon Empire staged an attempted invasion of Cardassia, and withdrew from the Khitomer Accords when the Federation refused to support the invasion. When Deep Space 9's crew discovered that the Detapa Council members had not been replaced with Founders, Gowron decided to back down rather than lead the Empire to its worst defeat ever. But the Martok Changeling had succeeded in turning two of the major powers of the Alpha Quadrant against each other. (DS9 episode: "The Way of the Warrior")
Odo later exposed the Martok Changeling on the Klingon station Ty'Gokor in front of a large crowd of Klingons. The assembled Klingons fired their disruptors into the Changeling repeatedly until he exploded. The real Martok was later rescued and returned to the Empire, playing a vital role in the Dominion War. The fact that Martok's Changeling replacement was responsible for the deaths of so many Klingons was a source of great shame to the real Martok, despite Worf's reassurance that he was not to blame. (DS9 episodes: "Apocalypse Rising", "By Inferno's Light")