Ian McDiarmid (born August 11, 1944) portrayed Palpatine/Darth Sidious in the Star Wars films. He appears in every film of the prequel trilogy, as well as in Return of the Jedi and The Rise of Skywalker. He is one of the three actors to have appeared in all three Star Wars trilogies along with Kenny Baker (R2-D2) and Anthony Daniels (C-3PO). He did not play the Emperor in the original release of The Empire Strikes Back, but was edited in for the 2004 DVD release of the original trilogy and subsequent releases. McDiarmid also worked with George Lucas on the 1992 television series The Young Indiana Jones Chronicles, in which McDiarmid portrayed Professor Levi in the episode "Paris, October 1916."
McDiarmid reprised his role in one scene in the sixth episode of the Obi-Wan Kenobi television series. His scene was filmed against a blue screen. Director Deborah Chow told him to film his scene between being on an edge and having some lines be more casual. McDiarmid struggled with remembering to use the word "execute" during filming.
McDiarmid has also had a distinguished career in British theatre, working as Associate Artistic Director for the Royal Exchange Theatre, Manchester (1986–1989), joint Artistic Director at London's Almedia Theatre (1990–2002) and as a Board Member of the National Theatre of Scotland. Recent and upcoming projects include a return to the role of Teddy in Brian Friel's Faith Healer (for which he won a Tony award) and in the world premiere of Robert Holman's Jonah & Otto, which marks his return to the Royal Exchange.