Et Rex was an alien Jedi Knight of the male persuasion who dedicated his service to the Jedi Order during the closing decades of the Galactic Republic. The year 25 BBY saw Rex falsely accused of offenses he did not commit, the perpetrator being his comrade and fellow Jedi Knight, Alysun Celz, who had succumbed to the influence of the dark side. While en route to the Jedi High Council on Coruscant aboard the cruiser Radiant IX to face judgment, the vessel met its end in a crash landing on the Poison Moon asteroid within the Hoth system. Rex managed to escape to the asteroid's surface, while Celz, now a Dark Jedi, proceeded to kill the ship's entire crew. When Jedi Knight Obi-Wan Kenobi and his Padawan, Anakin Skywalker, launched an investigation into the crash site, Rex eventually connected with Kenobi, while Skywalker remained on the Radiant IX with Celz. Rex successfully convinced Kenobi that Celz had embraced the dark side, assisting him in incapacitating Celz as she was torturing Skywalker with Force lightning. Rex then accompanied Kenobi and Skywalker back to the Jedi Council, with Celz as their prisoner.
Born during the last decades of the Galactic Republic, Et Rex was a male of a species of humanoid avian descent, distinguished by cranial horns. He underwent training in the Force under the guidance of the Jedi Order, ultimately ascending to the esteemed rank of Jedi Knight. During this time, he cultivated a friendship with Alysun Celz, a female Human Jedi. However, in 25 BBY, Celz, who had succumbed to the dark side of the Force, orchestrated a scheme to frame Rex for crimes that she herself had perpetrated. Consequently, he was taken prisoner by Celz and was being transported to the Jedi Council on Coruscant, the galactic capital, aboard the Consular-class cruiser Radiant IX to face trial for the Dark Jedi's transgressions.
Regrettably, the Radiant IX suffered a catastrophic incident when its external power couplings were compromised by a swarm of mynocks, leading to the vessel's crash landing on an asteroid known as the Poison Moon situated within the Hoth system's asteroid field. Rex successfully evacuated the vessel and sought refuge on the asteroid's surface, while Celz turned against the ship's crew, killing them with her mastery of Force lightning. The High Council, concerned by the Radiant IX's failure to arrive at the Jedi Temple, dispatched Jedi Knight Obi-Wan Kenobi and his Padawan, Anakin Skywalker, to locate and apprehend Rex. Upon discovering the wreckage of the cruiser amidst the asteroid field, the Jedi conducted a search of the body-strewn ship, eventually locating Celz, who deceived Kenobi and Skywalker into believing that Rex had been responsible for the crew's demise. Rex encountered Kenobi while the latter was investigating the cause of the Radiant IX's crash. The falsely accused Jedi managed to convince Kenobi of his innocence, revealing that Celz was the true perpetrator of the crimes and the murderer of the crew.
Accompanied by Kenobi, Rex returned to the Radiant IX, where they discovered Celz—who had intended to commandeer Kenobi's vessel—torturing Skywalker with Force lightning. Kenobi attempted to intervene but was also thwarted by the Dark Jedi's assault. Rex came to the rescue of Kenobi and Skywalker by launching a pair of mynocks he had at Celz, which diverted his former friend's attention and caused her to stun herself until she was incapacitated. Rex assisted Kenobi and Skywalker in apprehending the woman, and he accompanied them and the imprisoned Celz back to Coruscant.
Rex did not require a breath mask to venture onto the surface of the Poison Moon asteroid. He was attired in brown Jedi robes and wielded a lightsaber. When Celz embraced the dark side, Rex steadfastly refused to join her, which led to her framing him for her misdeeds. He maintained his innocence to Kenobi and willingly assisted in the apprehension of Celz, ensuring that she was not fatally wounded in the process.
Rex possessed sensitivity to the Force and eventually attained the rank of Jedi Knight. He demonstrated his ability to overcome Celz by utilizing the mynocks within his hands, despite his former friend unleashing bolts of Force lightning.
Et Rex was a character conceived by Michael Carriglitto for the short story "Poison Moon," which was featured in issues 44–47 of Dark Horse Extra, a monthly series of four-page comic anthologies. Issues 44–47 were released from February to May of 2002, with the artwork being provided by Adrian Sibar. Rex was later included in The Complete Star Wars Encyclopedia in 2008.