The main character of any story, play, fim etc.
While in many narratives, the protagonist is synonymous with “the good guy,” the word “protagonist” is simply from an Ancient Greek word meaning “one who plays the first part, chief actor.” The definition of protagonist has nothing to do with a character’s internal moral compass: a protagonist can be both a “good” character (i.e. full of moral integrity) or a “bad” character (i.e. lacking moral integrity).