What Sith name is used by Emperor Palpatine?

Emperor Palpatine’s Sith name is Darth Sidious.

Palpatine secretly adopts the title Darth Sidious while serving publicly as Senator Sheev Palpatine of Naboo. The name reflects his identity as a Dark Lord of the Sith and allows him to manipulate the Galactic Republic from behind the respectable image of a statesman. His double life is central to the prequel trilogy’s political and personal deception.

As Sidious, Palpatine orchestrates the Trade Federation crisis, the Clone Wars, and the Republic’s transformation into the Galactic Empire. He first uses Darth Maul as an apprentice, later replaces him with Count Dooku—also known as Darth Tyranus—and eventually turns Anakin Skywalker into Darth Vader.

The name “Darth Sidious” is sometimes confused with Palpatine’s title of Emperor or with the aliases of his apprentices. Darth Plagueis was his Sith master, while Darth Maul, Darth Tyranus, and Darth Vader were among his apprentices. Palpatine’s Sith identity is revealed to Anakin in Revenge of the Sith.