Mustafar (ˈmʊstəfɑːr) is a fictional volcanic and lava planet in the Star Wars franchise. Introduced in the final prequel film, Revenge of the Sith (2005), it also appeared in the films Rogue One (2016) and Episode IX – The Rise of Skywalker (2019). The lava planet consists largely of volcanic environments, featuring lava rivers and active volcanoes. It is mostly remembered for the role it played in Revenge of the Sith, being the site of a climactic lightsaber duel between Obi-Wan Kenobi and his former pupil, Darth Vader, which resulted in the latter's disfiguration and need of life support. The planet also featured in various spin-off media, including the VR game Vader Immortal: A Star Wars VR Series (2019), which reveals that Mustafar used to be a forested planet, and explores the origins of its current state.
While franchise creator George Lucas was writing the sequels of the original Star Wars trilogy, he outlined the backstory that would eventually be seen in the prequel trilogy, including the climactic duel between Jedi Master Obi-Wan Kenobi and Sith Lord Darth Vader (formerly Kenobi's pupil, Anakin Skywalker). In the novelization of Return of the Jedi, Obi-Wan recounts his battle with Anakin, stating that the latter "fell into a molten pit".
During the pre-production of Revenge of the Sith, Steven Spielberg was brought in as a "guest director" to make suggestions to the art designers for the duel scene. He suggested that Anakin and Obi-Wan should be "dripping sweat" and that "their hair at some point should be smoking", which Lucas loved. While the film was in production, Mount Etna erupted in Italy. Camera crews were sent to the location to shoot several angles of the volcano that were later spliced into the background of the film; 910 artists created 49 seconds of footage for the duel over 70,441 man hours.
In the anthology film Rogue One, Vader is depicted as having his personal headquarters on Mustafar. In creating the design for Vader's fortress, the film's developers drew inspiration from a Ralph McQuarrie concept painting from the original trilogy depicting Darth Sidious enthroned over a lava lake.