Emperor Palpatine

Emperor Palpatine, dark-side master and tyrannical leader of the Galactic Empire, was the greatest known evil in the galaxy. Using his deadly apprentice, Darth Vader, as his weapon, Palpatine dismantled the Jedi order and almost vanguished the powers of the Rebellion. He would have done so if it were not for his ignorance towards the love between Luke Skywalker and his father, Anakin.

It was when Palpatine expressed to Vader his concerns over Luke, that he would be a very powerful Jedi, that Vader suggested that the two convert Luke to the dark side of the Force. During the Battle of Endor, Palpatine concentrated on converting Luke to the dark side, even if it meant sacrificing Vader. Luke refused the Emperor's power, so Palpatine used his lethal force-lightning to attack him. Luke almost died during this, but Vader, returned to the good side of the Force, and tossed the Emperor into the Death Star's reactor core, which killed him.