Exar Kun. He enslaved an entire planet (Yavin IV, yes the planet from New Hope). He also took on several hundred Jedi when the Old Republic was in it's prime and didn't exactly lose. Instead of dying, he drained the entire native population of the planet's life force and used it to bind his spirit to the Sith temples there.
He resurfaced 4000 years later to kill some of Luke's Jedi students and put Luke in to some sort of coma-like state. He also converted a student to the dark side, who then went on to steal the Sun Crusher (size of a tie fighter, invulnerable, and more powerful than the death star). Kun was eventually defeated, but I know in the future some author is gonna use him again because of his shear badassery.
He INVENTED the double-bladed lightsaber (don't you dare say it was Maul), could change the length and intensity of it at will, throwing off his opponents, and he could fly. I'll say it again, HE COULD FLY. Oh, and this was before he found Sith artifacts that amplified his power many, many times over.
He did a whole lot more evil things that I'm too lazy to list, so here's a very limited wiki page on him.
http://starwars.wikia.com/wiki/Exar_Kun
He resurfaced 4000 years later to kill some of Luke's Jedi students and put Luke in to some sort of coma-like state. He also converted a student to the dark side, who then went on to steal the Sun Crusher (size of a tie fighter, invulnerable, and more powerful than the death star). Kun was eventually defeated, but I know in the future some author is gonna use him again because of his shear badassery.
He INVENTED the double-bladed lightsaber (don't you dare say it was Maul), could change the length and intensity of it at will, throwing off his opponents, and he could fly. I'll say it again, HE COULD FLY. Oh, and this was before he found Sith artifacts that amplified his power many, many times over.
He did a whole lot more evil things that I'm too lazy to list, so here's a very limited wiki page on him.
http://starwars.wikia.com/wiki/Exar_Kun