The Protagonist is the principal character of a story. Many are
Hero Protagonists but not all of them are. Beyond any and all other traits, whether they are a
Villain Protagonist,
The Hero, or simply an
Innocent Bystander, and whatever the stories POV may be, you can generally tell who
the protagonist is because the story is
about them. This is present in the vast majority of all fiction, marking it as one of the rare
Omnipresent Tropes.
Compare and contrast
The Antagonist, who is equally important because they oppose the actions of
the protagonist. Also see
Deuteragonist, the other character whom the story is about, but to a lesser extent than
the protagonist; in other words, a secondary
main character.