In "Star Wars: Episode III", who do the Jedi think is affiliated with the Sith?

In “Star Wars: Episode III,” the Jedi identify Supreme Chancellor Palpatine as affiliated with the Sith. He is secretly Darth Sidious, the Sith Lord manipulating the Clone Wars from within the Republic government.

Palpatine’s public identity helps conceal his role. As Chancellor, he appears to be a political leader defending the Republic, while secretly directing both sides of the conflict. The Jedi eventually learn that the Sith mastermind behind the war is connected to the Chancellor, prompting Mace Windu and other Jedi Masters to confront him in his office.

The film’s major revelation is stronger than a mere alliance: Palpatine himself is the Sith Lord. After revealing his powers, he defeats most of the Jedi team and later transforms the Republic into the Galactic Empire. Anakin Skywalker’s intervention allows Palpatine to survive and helps set Anakin on the path to becoming Darth Vader.

A common mix-up is Darth Tyranus, or Count Dooku, who is also a Sith but serves as Palpatine’s apprentice and political proxy—not the hidden ruler the Jedi are seeking.