Everett Vaughn is the captain of the former Terran Dominion flagship Bucephalus. Unswervingly loyal to Valerian Mengsk, he trusted the Heir Apparent enough that he didn't object to working with the Dominion's sworn enemy, Jim Raynor, and fighting against the Emperor of the Dominion himself, Arcturus Mengsk. He was described as young, although already going grey.
Everett Vaughn was given his first command of the Bucephalus days before the Battle of Char. After the successful deinfestation of Sarah Kerrigan, he was caught in the conflict between Arcturus Mengsk and Valerian Mengsk, and commanded the Heir Apparent's battlecruiser against Arcturus's fleet. Vaughn navigated through the battle, and after the Hyperion gave them an opening warped the ship out of harms way. However, the Bucephalus was bugged by Arcturus, and they were tracked. Vaughn once again found himself up against the Dominion fleet while Rory Swann attempted to rid the ship of bugs.
The renegades fled to Dead Man's Rock, and Vaughn stayed behind with the ship. However, he noted when a fleet of mercenary ships began firing on the debris protecting the criminal hideaway. Rory Swann wanted to escape, but Vaughn wanted to not be drawn out by the mercenaries flushing them out. Swann ignored him and began break from their scrap heap cover. Vaughn and Swann later attempted to escape the atmosphere, with Vaugh swinging around to rescue their allies stranded on the surface of Dead Man's Rock.
Using navigator Travis Rawlins, the Bucephalus was guided to the Moebius Foundation Space Station Prometheus. However, the ship was sabotaged by Moebius engineers, who were secretly working for Arcturus Mengsk. Vaughn conferred with the ship's chief engineer Elias Thompson, and he demanded that the weapons be brought back online. In a desperate gambit, Vaughn and Matt Horner attempted a desperate tactic, where the Hyperion would jump behind the Dominion flagship, the White Star, and surround it. The Bucephalus escaped, but jumped back to aid the Hyperion, providing cover fire for its escape. The two ships took the remaining personnel from the station aboard, and fled into a field of destroyed asteroids. Using the dust cloud, they were able to elude the Dominion fleet and escape to the Umojan Protectorate.