Exo was a protocol droid who assisted a spy in the Rebel Alliance. The spy obtained schematics for a key factory of the Galactic Empire, who tracked down and destroyed their base. Exo and the spy were the only survivors of the attack, escaping into hyperspace, but were pursued by Imperial Commander Tylux, who refused to fail the Empire. Using Tylux's determination to capture the spy at any cost, the two rebels led the commander into a trap that left his Star Destroyer disabled, allowing a rebel fleet to emerge and destroy it.
The spy and Exo flee from a devastating Imperial attack.
During the time of the Galactic Empire, Exo served the Alliance to Restore the Republic, working alongside a human male spy. After the spy discovered the schematics to a key Imperial factory, Commander Tylux of the Star Destroyer Bellicose led an attack on the base of the rebel forces, killing all of the cell besides Exo and the spy. The two escaped into hyperspace in a U-wing, hiding in an asteroid field above a nearby desert planet.
Commander Tylux, afraid of disappointing the Sith Lord Darth Vader for losing the spy, followed the craft into the asteroid field. The spy urged Exo to take control of their starship as several TIE fighters pursued them. Surrounded by the fighters, the spy ordered Exo to pilot the U-wing into the atmosphere of the planet. Exo was hesitant to do so due to the planet's extreme sandstorms, but the spy insisted that it was the only idea they had left.
Despite Tylux's efforts, the rebels ultimately escaped capture.
Regardless of the dangers of the sandstorm, Tylux sent his entire fighter wing down to the planet to follow the spy. The storm blinded the fighters' sensors and overheated their engines, allowing Exo and the spy to escape the planet before their own engines overheated. The spy destroyed the remaining TIEs, but Tylux refused to fail Vader, and chose to pursue his target in the Star Destroyer, flying through the asteroid field.
As a trap for the unyielding commander, the rebels piloted their craft into the mouth of a nearby exogorth, with Tylux following them. The spy blasted through the side of the creature, and Tylux's attempts to bring in the rebel vessel using his Star Destroyer's tractor beam failed due to the numerous mynocks sustained from the exogorth. With the Star Destroyer disabled, a Rebel Alliance fleet exited hyperspace above the planet, and destroyed the Imperial craft, rescuing Exo and the spy.
A protocol droid with feminine programming, Exo possessed blue plating and yellow photoreceptors. While attempting to escape the pursuit of Commander Tylux, Exo was hesitant about her captain's ideas and panicked about their situation as Imperial TIE fighters chased them through the sandstorms of the desert planet. Exo shared the spy's astonishment over Tylux's persistence in hunting them down.
Exo helped to pilot the rebel spy's UT-60D U-wing starfighter/support craft in their escape from Commander Tylux.
Exo appeared in the comic Vader - Dark Visions 2, written by Dennis Hallum, illustrated by Brian Level, and published by Marvel Comics on March 27, 2019.