Sheev Palpatine (also known as Senator Palpatine, Supreme Chancellor Palpatine, Emperor Palpatine, Darth Sidious, or simply The Emperor) is a fictional character and the main antagonist of the Star Wars universe, primarily portrayed by Ian McDiarmid.
In the original trilogy, he is depicted as the aged, pale-faced Emperor of the Galactic Empire. In the prequel trilogy, he is portrayed as a charismatic Senator from Naboo who uses deception and political manipulation to rise to the position of Supreme Chancellor of the Galactic Republic.
Though outwardly appearing to be a well-intentioned public servant and supporter of democracy prior to becoming Emperor, he is in fact Darth Sidious, the Dark Lord of the Sith – a cult of practitioners of the dark side of the Force previously thought to have been extinct in the galaxy for a millennium. As Sidious, he instigates the Clone Wars, all but destroys the Jedi, and transforms the Republic into the Empire. He also corrupts Anakin Skywalker to serve at his side as Darth Vader. Palpatine's reign comes to an end due to Luke Skywalker. More: en.wikipedia.org.