4. Katherine Pierce, The Vampire Diaries
Katherine Pierce, the doppelgänger of Elena, embodies the definition of the word villain. She’s only loyal to herself, and her only goal in life is being #1, despite what happens to others in the process. She often comes between Damon and Stefan, who both love her, and often pretends to be Elena when it works for her. And that’s not even mentioning what she did to Jeremy. She might just be the scariest monster on the show to date.