Sheev Palpatine, also known by his Sith name Darth Sidious, is a fictional character in the Star Wars franchise created by George Lucas. Initially credited as the Emperor in the original trilogy films, The Empire Strikes Back (1980) and Return of the Jedi (1983), he serves as the main antagonist of the nine-film Skywalker saga, in which he is portrayed by Ian McDiarmid.

In the original trilogy, Palpatine is depicted as the Emperor of the Galactic Empire and the master of Darth Vader. In the prequel trilogy, he is portrayed as a charismatic politician—and, secretly, a Sith Lord—who orchestrates the Clone Wars, all but exterminates the Jedi Order, ends the Galactic Republic, and seduces Jedi Knight Anakin Skywalker to the dark side of the Force. In The Rise of Skywalker (2019), the final film in the sequel trilogy, Palpatine is revealed to be the mastermind behind the First Order and the creator of its former leader, Snoke, as well as the grandfather of protagonist Rey, with Snoke, and Rey’s father, Dathan, being strand-cast failed clones of him. The character also recurs throughout the animated series Clone Wars (2003–5), The Clone Wars (2008–14; 2020), Rebels (2014–18), and The Bad Batch (2021–present), and the live-action miniseries Obi Wan Kenobi (2022), all set between the events of the prequel and original trilogies.

Since the release of Return of the Jedi, Palpatine has become a widely recognized symbol of evil in popular culture, and since the prequel films, also one of sinister deception and the subversion of democracy. Aside from the films, Palpatine appears in various canon and non-canon Star Wars media.