A human male strong in the Force, Thexan was a member of the Eternal Empire. Born to Emperor Valkorion and Senya Tirall, he participated in numerous conflicts for the Eternal Empire. His life was cut short in a swift lightsaber duel, where he died at the hands of his twin brother, Arcann.
As a son of Emperor Valkorion, the leader of the Eternal Empire, and Senya Tirall, a Knight of Zakuul, Thexan's upbringing was unique. Alongside his twin brother Arcann, he underwent rigorous warrior training from a young age, and Thexan was a constant source of support during difficult moments. While the twins and their younger sister, Vaylin, largely disregarded their mother, their father showed them little attention during their formative years. Despite Thexan's efforts to soothe his brother, Arcann's resentment towards their father grew steadily.
When Vaylin's escalating power and unstable mental state compelled Valkorion to confine her on Nathema to manage her abilities, Thexan made frequent visits to her. He shared his sister's aversion to the planet's void in the Force.
Eventually, upon reaching adulthood, Arcann rescued Vaylin from Nathema. Subsequently, Valkorion gifted Vaylin her first lightsaber. The twins instinctively moved to defend, the moment their sister ignited her blade, but stopped at their father's command. Vaylin then deactivated her weapon and pledged her loyalty to Valkorion.
Around 3636 BBY, Arcann and Thexan sought their father's approval to spearhead an offensive aimed at assessing the strength of the major galactic powers. They engaged in combat across numerous planets, pushing back both the Galactic Republic and the re-established Sith Empire. During this period of conquest, Arcann and Thexan launched an attack on Balmorra before ultimately targeting the Sith world of Korriban. During the attack on Korriban, Arcann suffered the loss of his arm and severe facial scarring, with Thexan remaining by his brother's side following the injury. Soon after the assault on Korriban, Thexan was tasked with reporting the invasion's progress to his father.
Later, Arcann and Thexan presented lightsabers taken from fallen Jedi and Sith as war trophies to their father. However, Valkorion's silent dismissal enraged Arcann, who, consumed by the dark side of the Force, attempted to attack the Emperor. Thexan used telekinesis to restrain his brother. Arcann then turned his aggression towards his brother, striking him down with a fatal blow to the stomach. Regaining his senses, Arcann held his twin's lifeless body, only to see Valkorion standing over him, who then asked his surviving son to accompany him.
A public funeral was subsequently held, falsely claiming that he had been killed in the Core Worlds. The true circumstances of his death remained concealed from everyone, including Senya, for five years, until Vaylin revealed the truth during the Battle of Asylum.
Years after his demise, Thexan joined forces with his family and all others wronged by Valkorion in eradicating the ancient entity's last vestige. He also extended forgiveness to his brother for his past transgressions.
Thexan's initial appearance was in Sacrifice, a cinematic trailer created by Blur Studio for Star Wars: The Old Republic's fifth digital expansion, Knights of the Fallen Empire. The trailer debuted at the Electronic Entertainment Expo on June 15, 2015. While his name was not spoken, Thexan's name can be identified in Aurebesh on his crib at the trailer's beginning. Erik Todd Dellums provided his voice, also voicing his twin brother Arcann.