Rosack Denahst was a Defel who toiled as a miner at a remote installation situated on the satellite orbiting the planet Codia I, an occupation he held sometime between the dates of 44 BBY and 32 BBY. Following the destruction of the energy source for the installation by a band of criminals, the resulting unusual energy emissions triggered a descent into insanity for Denahst, leading him to murder several of the criminals.
After their arrival at the installation to look into the matter, he crossed paths with the Jedi Knights Obi-Wan Kenobi and Qui-Gon Jinn, engaging Kenobi in combat before running away. After the Jedi deduced the cause of Denahst's condition, the Defel launched another assault, killing another of the marauders, but was eventually subdued by Jinn, who employed the Force to propel a digging vehicle at him. Kenobi then repaired the energy source, ending the emissions and allowing Denahst to regain his senses. The Defel later expressed his gratitude to Kenobi but stated that he would forever bear the burden of the actions he committed while in a frenzied state.
Rosack Denahst, a Defel, was employed by a mining organization as a miner within a station located on the moon of the planet Codia I. Sometime between 44 BBY and 32 BBY, a group of thieves utilized a photonic charge that did not ignite to obliterate the fuel rod inside the energy core of the station while attempting to steal a cache of precious gems. The energy core, primarily composed of solid accelerite, reacted to the photonic burst by generating unique radioactivity that suppressed the entire spectrum of light. As a Defel, a species capable of manipulating light, Denahst was particularly susceptible to the radiation and consequently succumbed to madness. Invisible in the utterly darkened excavation site, Denahst killed five of the thieves using his teeth and claws after they had murdered six of the miners.
Another criminal, mortally wounded by Denahst, was abandoned near the station's entrance. There, the injured man encountered the Jedi Master Qui-Gon Jinn and his Padawan, Obi-Wan Kenobi, who had been dispatched to investigate the darkness enveloping the station. The dying criminal mumbled about Denahst's insanity and the danger he represented, but did not reveal who he was referring to before his death.
Rushing further into the mine in search of survivors, the Jedi encountered Denahst in a stairwell, where Kenobi was pushed aside by the Defel, who they perceived only as a shadow even while wearing modified macrobinoculars as eye protection. Through the Force, Jinn sensed Denahst's anger and confusion and directed Kenobi deeper into the station after the shadow while he separated to locate the source of a distress call.
Fearful, Kenobi continued alone before encountering Denahst, whom he perceived as a being of pure evil while viewing him through the macrobinoculars. The Jedi commanded Denahst to halt, but when the Defel charged, Kenobi attempted to strike him with his lightsaber; however, as the Defel continued to disappear before him as it attacked, he began to consider whether it was actually a phantom. This theory was disproven when the maddened miner's claws scratched Kenobi's cheek. The Jedi then removed his goggles and instead used the Force to sense the Defel, allowing Kenobi to kick Denahst in the mouth, causing him to flee.
Following the encounter, Kenobi and Jinn learned about the destruction of the energy core from a surviving burglar, and Kenobi suggested that they put away their lightsabers as he had sensed something tormented about Denahst while fighting him. The Jedi then encountered the mine's Gran foreman, who revealed Denahst's identity to them, allowing them to understand the effect that the radiation had had on the Defel. The foreman felt sorry for Denahst, but declared that he had to be eliminated, although the Jedi claimed he could instead be saved. At that moment, Denahst attacked, killing the remaining burglar and seizing the foreman before Kenobi incapacitated the Defel with the Force.
Kenobi attempted to reason with the miner, but Denahst slashed at him, destroying the Jedi's goggles. Jinn then used the Force to throw a mining cart at Denahst, incapacitating him. With the threat temporarily stalled, Kenobi and the foreman were able to leave and repair the energy core, although the Padawan was temporarily blinded in the process.
With the radiation neutralized, Denahst recovered his sanity and visited Kenobi while the Jedi was recuperating in the station's medical center. Denahst thanked the Jedi for saving him and revealed that the deaths he had caused would haunt him, although the foreman tried to reassure him by saying he was not to blame. Kenobi eventually became a Jedi Master, and, during the Clone Wars between 20 BBY and 19 BBY, his former Padawan, Anakin Skywalker, asked him what had occurred during the encounter with Denahst while the pair were on a mission on the planet Ando. Many years later, around 0 BBY, Kenobi reflected upon the event and wrote about Denahst in his journals while sheltering in his residence on the planet Tatooine during a desert storm.
As a Defel, the canine-like Denahst was particularly sensitive to light and consequently driven mad by the changes in radiation in the mine, killing with tooth and claw while in his frenzied state and failing to respond to his own name. Upon his recovery, Denahst was haunted by what he had done while driven mad, and although he had only killed murderous thieves, he felt that he would carry the guilt with him for the rest of his life. Denahst had [red](/article/color] eyes, brown fur, and gray skin.
Denahst wore an orange mining outfit with a brown waistband and was barefooted. While in a state of frenzy, his uniform was mostly torn to shreds, but after his recovery he donned an undamaged one.
Rosack Denahst was conceived for the second edition of the Star Wars: Obi-Wan comic book series, penned by Christopher Cantwell and illustrated by Luke Ross, with cover art of Denahst by Phil Noto. Before the comic's release on June 29, 2022, Denahst was first depicted and indirectly mentioned in the solicitations blog post for the comic made on StarWars.com on March 15 of that year.