Belsavis recently made it’s debut with an on-screen namedrop in Episode 8 of Andor, with an Imperial Shoretrooper assigning prisoners to the planet. SWTOR players will recognise Belsavis as it featured heavily in the Vanilla game as the Republic’s dirty secret, planetary prison that lay host to the introduction of the Dread Masters.

However Belsavis was not created new for SWTOR, in fact it dates back to the mid 90s ‘Callista Trilogy‘ for Star Wars, appearing as a major story location in Book 1: Children of the Jedi, a novel series that succeeded the famous 90s ‘Jedi Academy Trilogy’ of EU novels.
While this was one of the only times before SWTOR where it was used, it was continuously referenced in EU novels set during the Phantom Menace and Attack of the Clones era, including the Boba Fett novel: Maze of Deception.

While it was made famous by SWTOR, Belsavis was first brought into Canon immediately after The Force Awakens, as it appeared in the Force Awakens themed TTRPG in 2016 and would then later be referenced in The High Republic: Light of the Jedi before being name dropped in Andor on screen.