Zythmnr was a temple priest of the Massassi species, a male individual who resided on the moon of Yavin 4 in the time leading up to the Great Sith War. He existed during the years before this conflict. Zythmnr was a member of a Massassi tribe with a lineage tracing back to the followers of Naga Sadow, the deceased Dark Lord of the Sith, who arrived on Yavin 4 around 5000 BBY. After rising to a position of influence within his tribe, Zythmnr chose to seclude himself, remaining in isolation for a period of twelve years. This Massassi priest reappeared in 3997 BBY, at the time when Exar Kun, a fallen Jedi Knight, was rendered unconscious during a clash with Massassi guards within a forest on Yavin 4. Zythmnr, in the belief that Kun was the individual they had anticipated, transported the bound Kun to the Temple of Fire, where he then summoned an ancient Sith wyrm in order to assess the former Jedi's capabilities. Kun, by taking possession of Zythmnr's potent Sith amulets, overcame the Sithspawn, thereby securing the loyalty of both Zythmnr and the other Massassi. Eventually, Kun deciphered the secrets of Sadow's Sith alchemy, discovering the means to transform a sentient being into a conduit of the dark side. Zythmnr volunteered to undergo this procedure, which successfully altered him into a Force-sensitive embodiment of the dark side.
A male Massassi by birth, Zythmnr was a native inhabitant of the moon called Yavin 4. He was a member of a Massassi tribe, the descendants of Naga Sadow's followers, a former Dark Lord of the Sith. These followers had sought refuge on Yavin 4 following Sadow's defeat in 5000 BBY at the second battle of Korriban. Sadow employed Sith magic to corrupt Zythmnr's forebears, turning them into savage beasts who channeled the dark side of the Force in their combat. By the time of Zythmnr, the Massassi tribe had a singular responsibility: to guard the Sith temples erected by their ancestors. Zythmnr eventually achieved the rank of temple priest and acquired a pair of Sith amulets. In 4009 BBY, he removed himself from society, spending the subsequent twelve years in solitude. In 3997 BBY, Exar Kun, a fallen Jedi Knight, journeyed to Yavin 4, prompted by the spirit of Freedon Nadd, a dead Dark Lord of the Sith, to deepen his understanding of the dark side of the Force. However, Kun was swiftly overcome by Massassi guards, and after Zythmnr's twelve-year period of isolation, he emerged to investigate Kun. The temple priest declared Kun to be the prophesied one and commanded that the Jedi be taken to the Temple of Fire.
Zythmnr instructed that Kun be restrained. Upon reaching the Temple of Fire, he accused the Jedi of intending to steal his Sith amulet. Despite Kun's denials, the Massassi priest labeled him a liar and ordered him to be cast into a pit within the temple. Zythmnr placed the Sith amulet on the broken statue of Naga Sadow. Subsequently, the priest and the other Massassi elders knelt, chanting ancient spells beneath the broken statues that lined the temple. Their incantations unleashed a powerful surge, accompanied by a throbbing rhythm and the odor of burning flesh, which permeated the temple. Suddenly, a Sith wyrm, created long ago through Naga Sadow's Sith alchemy as a guardian against the future Dark Lord of the Sith, materialized and attacked Kun. Drawing upon the power of the dark side, Kun used the Force to take Zythmnr's Sith amulet and employed its dark properties to vanquish the monster. Kun's demonstration of power secured the loyalty of the Massassi, including Zythmnr. Now in control of the Yavin 4 Massassi, Kun commanded Zythmnr's clan to construct temples that would concentrate vast dark side energies. The fallen Jedi began to delve into Sith alchemy, discovering a method to transform a living being into a manifestation of the dark side. Zythmnr consented to be the first subject of this ancient empowerment. Although the Massassi priest had reservations about the procedure, Kun reassured him, promising that it would be painless and that Zythmnr would become the greatest of all Massassi.
As the transformation commenced, Kun fused Zythmnr's skin with metallic bioarmor, enhancing the priest's bone structure and muscle mass. Zythmnr's claws sharpened to razor edges, and his hide hardened into plating. Despite Kun's assurances, the procedure inflicted excruciating pain upon the Massassi priest. Nevertheless, Zythmnr endured and urged the continuation of the experiments. Kun then infused Zythmnr with the dark side, using elements of his own physical makeup as a template. The priest responded well to the treatment and exhibited potential with the Force, prompting Kun to perform the same procedure on several dozen more Massassi.
Initially, Zythmnr harbored considerable contempt for Exar Kun, even threatening to kill him and unleash a Sith wyrm upon him. The Massassi priest was fiercely protective of his powerful Sith amulet, leading him to distrust Kun, whom he suspected of intending to steal them. He was also protective of his temple, accusing Kun of seeking to plunder it. Zythmnr was unwavering in his loyalty, pledging allegiance to Kun after the Jedi Knight proved his worth, and even agreeing to undergo experimentation after Kun uncovered the secrets of Sith alchemy. Despite his loyalty to Kun, Zythmnr remained hesitant and reluctant to undergo the procedure that would transform him into a dark side vessel. Zythmnr was bilingual, fluent in both the Massassi language and Galactic Basic.
Although not initially Force-sensitive, Zythmnr gained the ability to wield the power of the Sith amulet upon assuming the position of temple priest. However, after Exar Kun's discovery of Sith alchemy and his transformation of Zythmnr into a vessel of the dark side, Zythmnr became capable of touching the Force. With training, the Massassi priest demonstrated potential in the Force.
Zythmnr made his debut in Star Wars: Tales of the Jedi - Dark Lords of the Sith, a story arc within the Star Wars: Tales of the Jedi comic book series, authored by Kevin J. Anderson and Tom Veitch, and released from late 1994 to early 1995. Zythmnr appeared twice in Dark Lords of the Sith, specifically in the arc's fourth and fifth issues, and received indirect mention on the opening page of the sixth and final issue. In these depictions, Zythmnr was illustrated by Chris Gossett. Zythmnr also features in the Dark Lords of the Sith audio adaptation, although his name is not explicitly stated. Further details about the Massassi priest were provided in Bill Slavicsek and J.D. Wiker's 2001 Star Wars Roleplaying Game sourcebook, The Dark Side Sourcebook.
Within the Dark Lord of the Sith comics, Zythmnr communicated in the Massassi language, whereas in the audio drama, he spoke in Basic. For the purpose of this article, he is portrayed as being proficient in both languages.