Palpatine

Palpatine, also known as Darth Sidious, was a Sith lord. He was a galactic senator, later the chancellor of the Galactic Republic, and later the emperor of the Galactic Empire.

He is played by Ian McDiarmid in Episodes I through III, V, and VI and by Ian Abercrombie in The Clone Wars. In Episode V, he was originally played by Clive Revill (voice only) and Elaine Baker.