Darth Xarion, a male Sith Lord belonging to the Sith Empire, held a seat on the Dark Council around the year 3628 BBY.
Around 3643 BBY, Xarion was a male Sith Lord within the ranks of the Sith Empire. During the period known as the Cold War with the Galactic Republic, he engaged in a conflict with a rival Sith Lord named Anathel within the Stygian Caldera nebula. Their ongoing battle began to disrupt Imperial trade routes, leading a negotiator to persuade them to relocate their duel to another area within the Outer Rim Territories.
Subsequently, he rose to the rank of Darth and secured a position on the Dark Council by 3628 BBY, leading the newly established Galactic Influence sphere. In this role, Darth Xarion had oversight of Sith Intelligence and the former Sphere of Expansion and Diplomacy. His adversary, Darth Anathel, also served on the Council as the head of Sith Doctrine.
In the Jedi Under Siege update (5.10), NR-02 makes an indirect reference to Darth Xarion as their master, who is unable to communicate with the player at that specific moment. Darth Xarion's first actual in-game appearance occurs in Star Wars: The Old Republic: Onslaught, where he is depicted as a Dark Councillor. For players of the Republic faction who are secretly working as saboteurs for the Empire, Darth Xarion's identity is revealed, and he communicates with the player via holocomm within the Slippery Slopes Cantina.
For players aligned with the Imperial faction, after Darth Malgus's defeat on Elom, Xarion appears to assist in restraining him using the Force, leading to his arrest.