A protagonist is the main character in a drama. Technically, there can only be one protagonist in a drama, though writers often use the word in reference to two or more central characters. The antagonist is the main character’s chief opponent.
Because the protagonist is the main character in the drama—and because there can technically only be one—phrases such as main protagonist and central protagonist are redundant.
Katniss, the protagonist, is so mixed up from pretending to love a fellow contestant that she no longer knows what she feels. [New York Times]
And she seems to have created a proxy for herself with Arachne, Spider-Man’s ancient, eight-legged antagonist. [Slate]
So goes the tagline for “Almost Famous,” a movie in which the protagonist must negotiate the conflicting philosophies of a decadent world of rockstar debauchery and the intellectual gravity espoused by his mother. [Harvard Crimson]
She often looks as if she’s head-butting an invisible antagonist. [The Guardian]