A protagonist (from the Greek πρωταγωνιστής protagonistes, "one who plays the first part, chief actor") is the main character (the central or primary personal figure) of a literary, theatrical, cinematic, or musical narrative, which ends up in conflict because of the antagonist and with whom the audience is intended to most identify. In the theatre of Ancient Greece, three actors played all of the main dramatic roles in a tragedy; the leading role was played by the protagonist, while the other roles were played by deuteragonist and the tritagonist.

The terms protagonist and main character are variously defined and, depending on the source, may denote different concepts. In fiction, the story of the protagonist may be told from the perspective of a different character (who may also, but not necessarily, be the narrator). An example would be a narrator who relates the fate of several protagonists, perhaps as prominent figures recalled in a biographical perspective. Often, the protagonist in a narrative is also the same person as the focal character, though the two terms are distinct. Excitement and intrigue alone is what the audience feels toward a focal character, while a sense of empathy about the character's objectives and emotions is what the audience feels toward the protagonist. Although the protagonist is often referred to as the "good guy", it is entirely possible for a story's protagonist to be the clear villain, or antihero, of the piece.