villain

A villain (masculine), or villainess (feminine), also bad guy, baddy or baddie, is a stock character, whether based on a historical narrative or one of literary fiction. Random House Unabridged Dictionary defines such a character as "a cruelly malicious person who is involved in or devoted to wickedness or crime; scoundrel; or a character in a play, novel, or the like, who constitutes an important evil agency in the plot". The antonym of a villain is a hero.