The Sith immortal gods comprised a group of deities revered by the Sith and those who served them. Following the Battle of Endor, Darth Vader's aide, Vaneé, who was a Sith Lord's servant, invoked these gods while performing a ritual intended to bring Vader back to life.
Within canon, the Sith's immortal gods received a mention in the initial issue of the Star Wars Adventures: Ghosts of Vader's Castle comic series from 2021. Conversely, in the Star Wars Legends storyline, the gods were initially referenced in the sixth issue of the original Star Wars comics series dating back to 1977.