She proved herself to be the greatest erudite of her time along with Revan - Moddb.com (Darth Revan's Sith Holocron:)
I'm not entirely sure who's the most potent villain but I'm willing to admit that Vitiate is a superb anti-hero. And I hope he'll be mentioned in episode IX in some way. He was more of a dark entity than a mere force-sensitive person. And he learned the transfer-essence force-power.
Dooku.
Does Darth Traya count?
She proved herself to be the greatest erudite of her time along with Revan - Moddb.com (Darth Revan's Sith Holocron:)
I'm not entirely sure who's the most potent villain but I'm willing to admit that Vitiate is a superb anti-hero. And I hope he'll be mentioned in episode IX in some way. He was more of a dark entity than a mere force-sensitive person. And he learned the transfer-essence force-power.