Travis Mayweather is a mirror universe villain introduced in the Star Trek: Enterprise episode "In A Mirror, Darkly".
Just like his prime universe counterpart, he was portrayed by Anthony Montgomery.
By the early 2150s, Mayweather was a sergeant in the Terran Empire's MACO forces, serving on the Enterprise. Mayweather supported Jonathan Archehr when the latter attempted a mutiny against Captain Maximilian Forrest. Archer made Mayweather the head of his personal guard. After the mutiny was suppressed Mayweather was part of the boarding party that took control of the USS Defiant from the prime universe.
At Archer's orders, Mayweather severely beat several alien workers who had been working under the Gorn Slar to strip the Defiant of its technology. He later attacked Admiral Black's guard, enabling Archer to vaporize the Admiral with his 23rd-century hand phaser.
After the Defiant destroyed the ISS Avenger, Mayweather turned against Archer and helped Hoshi Sato kill Archer. He then supported Sato as she took control of the Empire as Empress Sato I. Sato later appointed him Captain of the Defiant, much to the consternation of his former superior officer Malcolm Reed.
Mayweather was killed in 2157 after having fallen out of Empress Sato's favor for failing to hunt down the rogue clone of Jonathan Archer. He was replaced by the mirror universe's version of A.G. Robinson.