What is a main character of a story called?

A protagonist (from Ancient Greek πρωταγωνιστής (protagonistes), meaning 'one who plays the first part, chief actor') is a main character of a story.

The protagonist is at the center of the story, makes the key decisions, and experiences the consequences of those decisions. The protagonist is the primary agent propelling the story forward, and is often the character who faces the most significant obstacles. If a story contains a subplot, or is a narrative made up of several stories, then each subplot may have its own protagonist.

The protagonist is the character whose fate is most closely followed by the reader or audience, and who is opposed by the antagonist. The antagonist will provide obstacles and complications and create conflicts that test the protagonist, thus revealing the strengths and weaknesses of the protagonist's character.