The protagonist is the main character of the story. Villains can be protagonists, just as heroes can be antagonists. The protagonist is not always the hero. That is why some writers prefer the "protagonist" over the word "hero". Villains could be the main characters of certain stories and heroes the antagonists. For example, "Macbeth" by Shakespeare. Macbeth was not the hero in that story. However, he was the main character.
