Ziliss, a pureblooded Sith Lord of the female persuasion, served as an enforcer for the Imperial Reclamation Service within the reconstituted Sith Empire during the Third Galactic War. In the year 3626 BBY, she, accompanied by fellow Imperial soldiers Dogah and Kodo, engaged the Alliance Commander, Arn Peralun, and Aryn Leneer upon their arrival at the Dantooine Jedi Enclave, where they sought to uncover the location of Darth Malgus. Ultimately, Ziliss and her comrades met their demise during this confrontation.
Within the video game Star Wars: The Old Republic, Ziliss makes an appearance as a boss character, introduced as part of the Onslaught expansion. Notably, her presence is exclusive to the Republic narrative; in the Imperial narrative, she is substituted by the Republic Captain Meinar. Within the Republic storyline, the player has the option to spare Ziliss, contingent upon their role as a saboteur secretly aligned with the Empire. Should she be spared, the droid NR-02 will relay Darth Xarion's gratitude to the player, while also noting that Ziliss continues to view the player as an "obnoxious, sanctimonious wart-hornet."