He was portrayed by Robert Foxworth, who later played the Romulan deep cover agent V'Las in Star Trek: Enterprise.
In the 2360s, Leyton was in command of the USS Okinawa. He promoted a young engineering officer named Benjamin Sisko to be his executive officer. After the Cardassians withdrew from Bajor Leyton recommended Sisko be named the commander of Deep Space Nine.
After Starfleet encountered the Dominion, Leyton began to feel that the Federation was too weak to defeat the Dominion, and began plotting a coup against President Jaresh-Inyo and the Fedeation council in order to turn the Federation into a military dictatorship with himself as leader.
As part of the coup he had a number of his supporters assigned to key positions within Starfleet. He had one of his people cause the Bajoran Wormhole to open without ships coming through, making it look like the Dominion was sending cloaked ships through the wormhole. Leyton also had the elite Red Squadron at Starfleet Academy sabotage Earth's power grid to make it look like the Changelings had sabotaged the planetary power array. He was able to talk Present Jaresh-Inyo into declaring martial law on Earth.
Meanwhile Benjamin Sisko started to become suspicious of Leyton's motives. He and the staff back on DS9 uncovered the truth, and the Defiant travelled to Earth to deliver evidence that Leyton was manipulating things to enable him to pull off a coup. Leyton sent the USS Lakota under Captain Erika Benteen to destroy the Defiant. However, Benteen had second thoughts about destroying the Defiant and stood down.
Sisko was able to talk Leyton into standing down. Martial law was ended a short time later, with the people of Earth deciding that if the Changelings wanted to destroy the peace on Earth they would have to do it themselves, the people of Earth would not give in to paranoia like the Changelings obviously wanted.
Leyton was court-martialed for his actions, and sentenced to five years of imprisonment at the New Zealand Penal Settlement. Sisko would later come to see him after Sisko manipulated the Romulans into joining the Federation in fighting the Dominion.
In the following 2372 Presidential election, Jaresh-Inyo was defeated after a single term in office. One of the key factors was the ease with which Leyton had been able to manipulate Jaresh-Inyo into declaring martial law. Jaresh-Inyo was succeeded by Min Zife, who favored a harder line stance against the Dominion.
After Leyton served his prison term in New Zealand he was released and faded in to obscurity and consistently refused to be interviewed. By 2386 high ranking Federation officials had no idea where he was. When Section 31 was exposed to the public, Attorney General Louvois had been surprised to learn that Leyton had in fact not been a 31 agent. Even so, Louvois made a mental note to track him down just to know where he was.
- His actor, Robert Foxworth also portrayed William Hague on Babylon 5. The General Hague character was intended to return for the Babylon 5 episode "Severed Dreams", but Robert Foxworth's agent had accidentally double booked him to appear as Admiral Leyton for the same time Severed Dreams was shot. Because of this the script for that episode was changed to have Hague dying off screen. An outtake from the episode had Ed Ryan actor Bruce McGill joking that Hague was doing Deep Space Nine and unable to join them.