Darth Immern, a Sith Lord of either Human or Sith pureblood heritage, was a member of the reconstituted Sith Empire. He fought against the Galactic Republic during the Great Galactic War. Becoming enraged, Immern executed all the crew members aboard his personal cruiser, which resulted in him being marooned in space. The Sith then had to rely on a maintenance droid, specifically MZ-12, to take care of the cruiser's operational systems. The astromech droid successfully navigated the starship to an Imperial station for resupply and repairs. Consequently, Immern invested a considerable amount of resources to enhance the droid's software so that it could function as his dedicated navigation unit. However, Immern perished during naval combat at the First Battle of Bothawui in 3671 BBY, leaving MZ-12 without a commanding officer.
The initial reference to Darth Immern occurred within the Codex entry pertaining to MZ-12. This entry was part of Galactic Starfighter, a digital expansion pack launched in 2013 for the 2011 video game, Star Wars: The Old Republic, developed by BioWare.