Protagonist

The word protagonist comes from vocabulary of ancient Greek drama, where it referred to the leading actor in a play.

Deuteragonist referred to the second actor, and tritagonist to the third actor, but these words are much less commonly used than protagonist is today, although the chorus still appears, notably in musical comedies. The character who opposes the protagonist is the antagonist.

In modern literary vocabulary, the protagonist is the lead character in a story. The word differs from "hero" in that a protagonist, well, doesn't have to be a hero. A villain can be the protagonist. An ordinary person can be the protagonist.

Protagonist is also a less gendered term than "hero', inasmuch as there is no modified counterpart to it as there in the case of "hero"/"heroine".