The Taming of the Shrew
Unlike most stories, the "Antagonist" in The Taming of the Shrew is not a character. Katherine and Petruchio, both protagonists, struggle with each other throughout the play. Most critics see Katherine's shrewish behavior as the "villain" because it's the thing that must be overcome in order for Kate and Petruchio to live happily ever after. The idea makes us a little queasy, but there it is.