HX-138

Following the Battle of Yavin, HX-138 found herself stationed at the Imperial Research and Prison Facility located on the world of Dathomir, alongside fellow stormtroopers KD-121 and GT-643. She was known to wear black Imperial Spec Ops Officer armor and was regarded as a Darktrooper.

In the year 1 ABY, an accident occurred within the Imperial Research and Prison Facility. The Blackwing virus being studied there broke free of its containment, devastating most of the facility's population and transforming them into ravenous undead beings. As a result, the Galactic Empire quickly established a Quarantine Zone to isolate the infection. HX-138, along with GT-643 and KD-121, were part of a group of stormtroopers, led by HX-138, who seemed to be immune to the virus. These stormtroopers survived the initial outbreak but were then trapped within the Quarantine Zone along with other survivors. To defend against the constant attacks by zombies and seek safety while awaiting rescue, the stormtroopers and refugees established a temporary settlement known as Camp Epsilon. Among these survivors were Zsu Val, a former prisoner, Sogan Varga, a technician, Nils Cridmeen, a mechanic, and Klex Fulgor, an Inquisitor. Camp Epsilon was very dangerous because it was situated in the courtyard of the Imperial Research and Prison Facility, which was home to the most dangerous undead. However, the camp was built around a Lambda-class shuttle, which was the only starship in the area that had not been destroyed during the outbreak. The ship was damaged and unable to fly, but Nils Cridmeen and HX-138 hoped to repair it so that the survivors could escape the Quarantine Zone.

During their time in the Quarantine Zone, a group of spacers visited Camp Epsilon. They helped HX-138 and the stormtroopers save some survivors and find parts to fix the shuttle. Later, the spacers left Camp Epsilon to enter the Imperial Research and Prison Facility to get a sample of the Blackwing virus. The spacers survived their mission and came back to Camp Epsilon. Meanwhile, Nils Cridmeen was able to fix the Lambda-class shuttle. The refugees of Camp Epsilon and the spacers eventually escaped the Quarantine Zone with the repaired shuttle.

HX-138 was a non-player character in the 2003 video game Star Wars Galaxies, a massively multiplayer online roleplaying game created by Sony Online Entertainment and released by LucasArts, before it was shut down on December 15, 2011. HX-138 was added to the game in "Game Update 14," also known as the "Death Troopers" update, which was released on October 12, 2009.

The name HX-138 was probably inspired by THX 1138.