The phrase "eponymous protagonist" refers to the main character in a story whose name is also the title of the book, movie, or series. They are central to the plot and the story revolves around them. Full definition
Lila Ames, the eponymous protagonist of Robinson's most recent novel, did not. (firstthings.com)
Watson is set to play the movie's eponymous protagonists, Belle, while Dan Stevens co-stars as her unlikely romantic suitor the Beast (formerly known as Prince Adam). (filmcutting.com)
Wadjda, both the first film to be shot in Saudi Arabia as well as the first to be directed by a Saudi woman, may not be infallible, but it is a sharp commentary that pierces to the heart of things just as well as its eponymous protagonist pierces our own hearts with her quirky, rebellious ways. (waytooindie.com)