A protagonist () is the main character in any story, such as a literary work or drama. 

The protagonist is at the center of the story, makes the key decisions, and experiences the consequences of those decisions. The protagonist affects the main characters' circumstances as well, as they are often the primary actor propelling the story forward. If a story contains a subplot, or is a narrative made up of several stories, then the 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 the antagonist. The antagonist will provide obstacles and complications and create conflict that 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 dramatic 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 invention of tragedy 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.
who introduced the second actor
Then the poet Aeschylus, in his plays, introduced a second actor,