"If [Darth] Vader is the great dark icon of our times, I'm blacker than him. I'm the blackest of the black," said Ian McDiarmid when speaking to Empire Magazine about his role as Emperor Palpatine/Darth Sidious, master of Vader and greatest villain of the "Star Wars" saga.

"Star Wars" emphasizes how the dark side leads to misery; Vader's portrayal across the original trilogy is about the rediscovery of humanity buried within a monster. Palpatine is the exception; he's an enigmatic sadist utterly devoid of conscience or attachment.

In the prequel trilogy chronicling his rise to Emperor, Palpatine orchestrates an invasion of his homeworld in a complex plot to ride the sympathy vote to the Chancellorship, sparks a ruinous galactic civil war, and ultimately ends 1000 years of democracy (though some might argue that he just hastened the end of the Republic's corrupt husk).

McDiarmid has played Palpatine on and off for...