The Siege of Mandalore is the collective name used to refer to the final story arc of the American 3D animated science fiction television series Star Wars: The Clone Wars. The story arc is composed of the episodes "Old Friends Not Forgotten", "The Phantom Apprentice", "Shattered", and "Victory and Death", which are respectively the ninth, tenth, eleventh, and twelfth episodes of the seventh season of the series.

The series chronicles various events in the Clone Wars, a galactic conflict between the Galactic Republic and the Separatist Alliance that takes place during the Star Wars prequel trilogy. It primarily follows Jedi Knight Anakin Skywalker and his closest associates as they seek to help the Republic win the war. The arc takes place before and concurrently with the events of the film Revenge of the Sith, and follows Ahsoka Tano and Rex as they seek to liberate Mandalore from Maul, who had occupied it. After Maul's capture, Ahsoka and Rex are then forced to deal with the effects of Order 66.

All four episodes were released weekly on the streaming service Disney+ in April and May 2020. The arc received critical acclaim, with reviewers finding it emotionally resonant and a worthy conclusion to the series.

Ahsoka Tano and Bo-Katan Kryze contact Anakin Skywalker and Obi-Wan Kenobi, asking them for help in apprehending Darth Maul in his new hideout on Mandalore. While Obi-Wan is apprehensive, Anakin and the 501st give Ahsoka a warm welcome until news arrives that General Grievous and the Separatists are attacking Coruscant. Upon Anakin's suggestion, Rex (field-promoted to commander) and part of the 501st accompanies Ahsoka to Mandalore, forcing Maul's loyalists under Gar Saxon into retreat. Bo-Katan apprehends Prime Minister Almec, while Ahsoka follows a trail into the city's tunnel network, only to walk right into Maul's trap.

Ahsoka faces off against Maul, who mentions Darth Sidious before escaping. Ahsoka relays this to Obi-Wan, who says he had inferred from the recently killed Count Dooku that Sidious is the name of the Sith Lord who orchestrated the Clone Wars. Obi-Wan stresses that Maul must be taken alive as he may be their only chance to learn more about Darth Sidious. The captured Almec mentions that Maul had hoped to lure Anakin to Mandalore, but is assassinated by Gar before he can reveal why. As Bo-Katan's and Rex's forces lead a final assault against Maul's Mandalorians, Ahsoka confronts Maul again, who reveals that Sidious has engineered the destruction of both the Galactic Republic and the Jedi and asks Ahsoka to join him to stop Sidious. When she demands to know his intentions with Anakin, Maul claims that Sidious wants to make him his new apprentice, and that he had hoped to kill Anakin before this happens. Refusing to believe him, Ahsoka fights Maul above the city, where she rescues him from falling to his death. She then leaves Maul to be captured by clone troopers, despite his frantic warnings that everyone will soon die.

With the Siege of Mandalore over, Ahsoka and Rex prepare to take Maul before the Jedi Council on Coruscant. Mace Windu and Yoda contact Ahsoka via hologram and reveal that Obi-Wan has tracked Grievous down to Utapau, indicating that the war may soon be over. On their way to Coruscant, however, Ahsoka senses Anakin falling to the dark side and helping Darth Sidious to kill Windu, moments before Sidious executes Order 66, which brands all Jedi as traitors to the Republic and orders their deaths. As Ahsoka's clone troopers, including Rex, suddenly turn on her, she is forced to escape. Rex resists the order just long enough to mention the incident with Fives, allowing Ahsoka to learn about the inhibitor chips. She releases Maul to create a distraction, then subdues and captures Rex. With the help of three astromech droids, Ahsoka removes the inhibitor chip from his brain, restoring his free will.

As Ahsoka and Rex try to escape from the cruiser, Maul destroys its hyperdrive, causing the vessel to drop out of hyperspace and into a nearby moon's gravitational field. Forced to fight their way through the clones, Ahsoka tries to prevent Maul from getting away in their shuttle but lets him get away after choosing to help Rex. Just barely clearing the doomed ship, Ahsoka and Rex escape to the moon, where they respectfully bury the clones and Ahsoka discards her lightsabers. Two years later, Anakin, now as Darth Vader, arrives on the moon and recovers Ahsoka's main lightsaber from the wrecked cruiser.

All four episodes that make up the story arc were written by Star Wars: The Clone Wars supervising director Dave Filoni. Following the purchase of Lucasfilm by The Walt Disney Company, the series was cancelled in March 2013 following the release of the fifth season on Cartoon Network, and midway through the production of the sixth of eight planned seasons. This left unreleased episodes in various stages of production, from completely finished episodes to episodes that were still in early development. The completed episodes were released onto Netflix on March 7, 2014, as a truncated thirteen-episode sixth season, subtitled The Lost Missions. Included in the unreleased episodes were plans of a series finale involving Ahsoka Tano and Rex fighting Darth Maul during the events of Revenge of the Sith, which had been written, originally by Matt Michnovetz, at the time of the series' cancellation. Despite the arc not having actually been released, Lucasfilm considered the events of the arc to have occurred within the Star Wars universe, affecting subsequent Star Wars media that was created during the following years.