Sidious, beyond the shadow of a doubt for me. Many people claim parts about his history, but we really know relatively little about his life as a man or his Sith Apprenticeship. Even his true age is shrouded in mystery, but again many have speculated, even mapping out a history of Palpatine's life, while other sources argue that it was based on the fictitious life and age of Palpatine that Sidious created for his public persona while he carried on the machinations behind the scenes. Finally to see Sidious revealed as he truly is in Episode III was unparalleled for me in moments of joy in the Star Wars universe (Dooku once described Sidious in the force as, "...beyond power. He showed nothing of what might be within. Though seen with the eyes of the Dark Side itself, Palpatine was an event horizon. Beneath his entirely ordinary surface was absolute, perfect nothingness. Darkness beyond darkness"). This was all explained well in the "Sithisis" storyline in "Star Wars: Visionaries" and expounded upon in a recent issue of Insider, based in GL's comments about Palpatine being the mask and Sidious being the real face of the most maligned character in the greater Star Wars lore in canon. It conveys Sidious in his true guise undergoing a Dark Sith ritual in the belly of the EmPal SuRecon Center (the tallest building on Coruscant/ the building where Vader undergoes his surgical reconstruction and final transformation/ Sidious' secret Sith Temple or Coruscant disguised as a meidcal center); there, he immerses himself in the power of the Dark Side using Sith crystals and holocrons to take on the appearance of the venerable Palpatine (this also explains why Palpatine looks younger in Episode III than in Episode II as he would have undergone these rituals after delving deep into his inner darkness). Sidious' actions with Plagueis can be summed up well in a line by Shakespeare, "Ambition should be made of sterner stuff." He knew that Plagueis had no intention of keeping him as Apprentice permanently, as he had been manipulating the midi-chlorians in hopes of conceiving the perfect apprentice through conception in the force. Sidious took this knowledge, but being that Plagueis' focus was always on the abstract rather than the here and now, Sidious killed him in the here and now, allowing his meditative master to become one with his studies rather than following out with the plans of the Sith as they should have been. After killing Plagueis, Sidious accelerated his plans, researched and eventually succeeded in conceiving the "ideal Apprentice," and plunged the Galaxy into a conflict, the whole time acting as puppeteer on both sides while on a gradual path to unequaled martinet of all the Galaxy. As a brief aside, I should note that he took Maul in Maul's early youth (sources differ as to whether this was childhood or infancy) and later while Maul was still his apprentice, Sidious seduced Dooku to the Dark Side, revealing his plans for the Sith and telling Dooku that eventually he would replace Maul (though since so much work was put into Maul's training - literally Maul's entire life - Sidious had no intention at the time of using Dooku as little more than a Dark Jedi disciple to aid in the later conflict, and it was only with Maul's death on Naboo when his plans were altered). It was not enough simply to conquer and rule, it was a matter of eliminating the misguided and disorderly Jedi, who only through their complicite blindness to the great well of power in the Force did they remain unseeing of the great power rising within the force and bending it to his will. The Clone Wars were a war of attrition for the Jedi, as it made them appear as warlords instead of contemplative guardians; their reputations were withered away in time, which eased the ability of casting them down with one swift stroke, once the "ideal Apprentice" (Vader) had come full circle, and within the very circle of the Jedi as the suspected Chosen One. Practically every single player in the Prequels, and many in the Classic Trilogy were little more than puppets on Sidious' ever-dancing strings, which is why he easily receives my vote :emperor .