- "I have failed you, Anakin. I have failed you."
"I should have known the Jedi were plotting to take over!"
"Anakin, Chancellor Palpatine is evil!"
"From my point of view, the Jedi are evil!"
"Well, then, you are lost!"
"This is the end for you, my master."
- ―Obi-Wan Kenobi and Anakin Skywalker/Darth Vader
The Duel on Mustafar was a confrontation where the recently-apprenticed Sith Lord, Anakin Skywalker/Darth Vader, fought his former best friend, and Jedi Master, Obi-Wan Kenobi, on the Outer Rim planet of Mustafar. After gaining knowledge of Skywalker's downfall from Grand Master Yoda at the Jedi Temple, Kenobi arrived on Mustafar, where he attempted to reason with Skywalker/Vader, not believing that Emperor Palpatine, also known as the Sith Master, Darth Sidious, had taken control of his mind. However, Skywalker/Vader no longer cared for their friendship, and quickly claimed that Kenobi was his enemy; the pair then ignited their lightsabers and locked blades, fighting through the murder scene in the Klegger Corp Mining Facility, where Skywalker/Vader had recently slaughtered the members of the Separatist Council, the legislative branch of the now-defunct Confederacy of Independent Systems.
The fight progressed on the structures of the massive facility that hovered over the deadly lava of Mustafar. Kenobi and Skywalker/Vader soon found themselves trapped on a structure collection arm connected on the facility when it was separated from the facility by the lava and descended onto a hot stream. Kenobi managed to fall onto a lava skiff that was heading in the opposite direction of the fallen collection arm in the stream. Skywalker/Vader soon followed and jumped onto a droid collector where the two continued to fight. Kenobi managed to jump onto a high lava bend slope, and claimed that the duel was over due to his advantage. The Sith attempted to follow, but Skywalker/Vader, in his hubris, failed to block Kenobi's final attack, a mou kei maneuver, which severed Skywalker's/Vader's remaining organic limbs, and Skywalker/Vader rolled down to the edge of the lava bend, bringing the duel to an end.
Then, Kenobi—overcome with remorse over his friend's transformation—cried out that he had believed that Skywalker/Vader was the Chosen One and his destiny was to destroy the Sith, but instead he joined them. Unable, but most likely unwilling, to connect with his former best friend, the Sith was consumed by the fires of the lava that leaked onto the lava bend; leaving Skywalker/Vader to die, Kenobi retreated and took his fallen apprentice's lightsaber. Afterwards, Vader's new master, Darth Sidious, found his injured apprentice and took him back to the galactic capital of Coruscant to be rebuilt; the suit that Vader donned there would be one that the Dark Lord would wear for the rest of his life.
During the Clone Wars, the Son lured Anakin Skywalker into the Well of the Dark Side and corrupted him with a premonition of the duel on Mustafar. The duel began after Darth Sidious, as the newly appointed Galactic Emperor Sheev Palpatine, tasked Anakin Skywalker/Darth vader, his new apprentice, with the assassination of the leaders of the Confederacy of Independent Systems on the volcanic Outer Rim planet Mustafar, in order to bring an end to the Clone Wars. Anakin was followed to Mustafar by his wife, Padmé Amidala, who he wounded after seeing Jedi Master Obi-Wan Kenobi; Anakin wrongly believed that Amidala had led Kenobi, his former master, to Mustafar in order to kill him.
The duel was a lengthy and brutal affair with neither of the combatants gaining the edge as neither of them wanted to win this fight. The duel took place across a Separatist installation on Mustafar, with the two combatants making their way through hallways, conference rooms, and command centers, the latter of which led to them inadvertently triggering a meltdown on the facility. As a result, the facility's shielding began to collapse under the heat and lava on the planet. The fight moved onto a lava river, before ending on an embankment where Skywalker's/Vader's left arm and both legs were severed. Following an impassioned indictment by Kenobi of how Anakin/Vader, believed to have been the Chosen One, was meant to destroy the Sith instead of joining them, Anakin's/Vader's body burst into flames from the lava and he was burned alive. Kenobi retrieved Anakin's lightsaber and remorsefully left him on the embankment presumably to die, before fleeing the planet with the dying Amidala.
Sidious sensed his apprentice's struggle from across the galaxy and personally travelled to Mustafar to retrieve him. Sidious then brought Vader back to Imperial Center, where he placed his badly-wounded apprentice into a cybernetic suit of armor that would keep him alive for the rest of his life. Kenobi, meanwhile, brought Amidala to Polis Massa, where she died shortly after giving birth to her and Anakin's twins, Luke and Leia Organa. Kenobi took Luke to Tatooine and went into exile, and would not meet Anakin/Vader again for several years. Their final living encounter took place on the Death Star, where Anakin fully embracing his Vader persona killed his former master. Years later at the Battle of Endor, Anakin, inspired by his son, found redemption, killing Sidious and rejoining Kenobi in the Force.
- Star Wars: The Clone Wars – "Ghosts of Mortis" (Vision to Anakin Skywalker)
- Star Wars: Episode III Revenge of the Sith (First appearance)
- Lords of the Sith (Indirect mention only)
- Star Wars: Episode IV A New Hope (First mentioned, indirectly)
- Star Wars: Darth Vader 1: Vader (Indirect mention only, in opening crawl)
- Star Wars: Darth Vader 6: Vader, Part VI (Indirect mention only)