In addition to being one of the most powerful supernatural beings of all time, Kai also pulled off one of the biggest spells of all time. OK, maybe not the biggest spell, but it certainly had a huge impact on TVD franchise. When Bonnie doubled-crossed Kai and left him in the 1903 prison world, Kai retaliated by putting Elena under a sleeping curse and linking her life to Bonnie's, meaning that Bonnie was forced to live out her life without her best friend. Though Bonnie was able to figure out how to reverse the spell by the end of the series, it certainly was one of the show's most memorable villainous moments.
