The main character who must struggle against opposing forces is called the protagonist. The protagonist is the main character in a work of literature - for example, Dorian Gray in "The Picture of Dorian Gray," or Harry Potter in his novels, or Frodo Baggins in "The Lord of the Rings." A hero doesn't necessarily have to be a protagonist - it can be any character in a novel. A villain is a bad guy - an antagonist, and is the opposite of a protagonist.