The protagonist is at the center of the story, should be making the difficult choices and key decisions, and should be experiencing the consequences of those decisions. The protagonist should be propelling the story forward. If a story contains a subplot, or is a narrative that is made up of several stories, then there may be a character who is interpreted as the protagonist of each subplot or individual story.
The word protagonist is used notably in stories and forms of literature and culture that contain stories, which would include dramas, novels, operas and films. In those forms the protagonist may simply be the leading actor, or the principal character in the story. More formally, the protagonist, while still defined as a leading character, may also be defined as the character whose fate is most closely followed by the reader or audience, and who is opposed by a character known as the antagonist. The antagonist will provide obstacles and complications for the protagonist; the antagonist will create conflict, which will test the protagonist — thus revealing the strengths and weaknesses of their character.
The earliest known examples of protagonist are dated back to Ancient Greece. At first performances involved merely dancing and recitation by the chorus. But then in Poetics, Aristotle describes how a poet named Thespis introduced the idea of having one actor step out and engage in a dialogue with the chorus. This was the invention of tragedy, which occurred about 536 B.C. Then the poet Aeschylus, in his plays, introduced a second actor, inventing the idea of dialogue between two characters. Sophocles then wrote plays that required a third actor.
Euripides' play, Hippolytus, may be considered to have two protagonists. The protagonist of the first half is Phaedra, until she dies. Then her stepson, the title character, Hippolytus, has the dominant role in the second half.
In Shakespeare’s play, Romeo and Juliet, Romeo is the protagonist. He is actively in pursuit of his relationship with Juliet, and the audience is invested in that story. The character of Tybalt opposes Romeo’s desires, he is the antagonist.
In the novel, The Catcher in the Rye, the character Holden Caulfield is the protagonist. He is the leading character, and the reader is invested in his story.
Sometimes, a work will have a false protagonist, who may seem to be the protagonist, but then may disappear unexpectedly. The character Marion in Alfred Hitchcock's film Psycho (1960) is an example.
A novel that contains a number of narratives, may have a number of protagonists. Alexander Solzhenitsyn's The First Circle, for example, depicts a variety of characters imprisoned and living in a gulag camp. Leo Tolstoy's War and Peace, depicts fifteen major characters involved in or affected by a war.