Gauer was an assassin and agent employed by the Galactic Empire, and a conspirator in Grand Moff Trachta's plan to overthrow the Sith in 1 BBY.
Gauer's exact species is unknown, but it seems he was from an unidentified Near-Human species. He was distinguished by his bald head, pale skin, yellow eyes, and extensive tattooing. Gauer was an experienced assassin, and he was usually employed by the Galactic Empire. Darth Vader considered Gauer capable of taking out lightsaber-wielding Force-sensitives, and a measure of his status may be gauged from his involvement in the anti-Sith conspiracy led by Grand Moff Trachta. The other key figures in the plot were Grand Moff Bartam, Moff Kadir and General Skosef. At first, Gauer objected loudly when Skosef introduced Kadir to the other conspirators, before he was silenced by Trachta.
Gauer's closest loyalties within the cabal seems to have been Bartam, but while he seems to have shared his fear that Trachta was planning to dispense with or sideline the other players, it was the ambitious Moff Kadir who eventually persuaded him that the conspiracy's putative head had to be removed from the equation.
When Grand Moff Bartam sent Gauer to eliminate Trachta, the cunning assassin infiltrated Trachta's personal quarters and programmed an armed droid to kill his target. Unfortunately, Trachta was able to see the droid and quickly destroyed it, but he did not notice Gauer who was hiding in the shadows. Gauer shot and killed the Grand Moff with his blaster pistol, but Bartam was murdered at the same time by General Skosef, under the orders given by Trachta.
When Trachta, Bartam and Skosef were dead, Gauer went to the Imperial Palace with Moff Kadir and the stormtroopers conditioned to serve the conspiracy. Unlike Kadir and his troops, Gauer didn't enter the Emperor's throne room, but he decided to stay outside the room. When his ally and the stormtroopers were ambushed by Palpatine's Royal Guard, Gauer fled from the Palace, apparently realizing that the coup attempt had failed.
Gauer was the only member of the conspiracy to escape alive.