Mustafar

"I've only heard that name once, from Kanan. He said Mustafar is where Jedi go to die."

- Hera Syndulla Mustafar was a small planet that appeared the Star Wars franchise. Located in the Mustafar system of the Outer Rim Territories, it was known as a fiery volcanic world where lava was mined like a precious natural resource.

Mustafar was a very young and volatile world, torn apart by opposing gravitational forces of the gas giants Jestefad and Lefrani, with the former being the closer of the two. Astride thick-skinned lava fleas, the natives leapt across the lava fields to mine the planet's deadly natural resources. Mustafarians oversaw the smelting facilities constructed by the Separatists on Mustafar.

Background
It was on this very planet that Darth Maul began his Sith training. It was also the last capital of the Confederacy of Independent Systems and the site of the Separatists' downfall, an event that shaped galactic history. It was the site of the climactic duel between Anakin Skywalker and his former master, Obi-Wan Kenobi. The duel ended with Anakin defeated and severally burnt by planet's harsh environment, resulting him to be concealed behind a mask for the rest of his life.

Mustafar later came under the control of the Empire after Emperor Palpatine ended the Clone Wars and brought the Empire to power, resulting in the fall of both the Jedi Order and the Republic. Afterwards, Mustafar became infamous for being the place where Jedi go to die. Shortly after Kanan Jarrus was captured, he was transported to Mustafar for further interrogation under the supervision of Grand Moff Tarkin, until he was later rescued by his fellow Rebels.

Trivia

 * The concept of Mustafar dates back to the development of Return of the Jedi, in which Luke Skywalker battles Darth Vader over a lava lake in Palpatine's throne room in the lowest levels of the Imperial homeworld. Even back then, it was rumored that Anakin suffered his grievous injuries at the hands of Obi-Wan during a battle over a lava pit, and the concept became an almost mythical tale among Star Wars fans until finally realized on film over twenty years later.
 * Mustafar bears a striking resemblance to Io, the fifth moon that orbits Jupiter. Like Mustafar, Io too experiences extreme volcanic activity on the surface. The obvious difference between Mustafar and Io is that Io's volcanic flows are made up of sulfur, whereas Mustafar's are made up of molten silicate rock and iron ore, which are much hotter than molten sulfur.