Emperor Palpatine, Darth Sidious
Scheming, powerful, and evil to the core, Darth Sidious restored the Sith and destroyed the Jedi Order. Living a double life, he was also Palpatine, a Naboo Senator and phantom menace.
He manipulated the political system of the Galactic Republic until he was named Supreme Chancellor -- and eventually Emperor – and ruled the galaxy through fear and tyranny.
The galaxy rejoiced when he died at the Battle of Endor, but Sidious had cheated death and patiently plotted a return to power.
(description of Palpatine provided by starwars.com/databank)