In The Tragedy of Julius Caesar, who is the protagonist, and why should this character be considered the play's protagonist?

The protagonist is the central character in a story. The writer intends for the audience to identify with and feel sympathy for his or her protagonist. In this tragedy, Brutus is Shakespeare's protagonist, even though the play bears Julius Caesar's name.

Brutus is the play's central character. It is his story that unfolds from the beginning of Act I through the conclusion of Act V. Shakespeare develops Brutus as an honorable man who struggles with a terrible conflict: to remain loyal to his good friend or to his beloved country. Brutus tries hard to do what he perceives to be right.

Brutus becomes even more sympathetic when the audience realizes that Cassius is not only encouraging Brutus to join the conspiracy to murder Caesar, but also tricking him. Cassius deceives Brutus by making him believe the citizens of Rome are begging him to protect their freedom. When Brutus does join the conspiracy, he does so believing that their cause is noble. After Caesar's assassination, when he disapproves of actions taken by Cassius, he reminds Cassius in a very emotional speech why they killed Caesar. He must  believe that Caesar's death was for the good of Rome.

At the play's end, a defeated Brutus chooses to die with honor. Shakespeare reminds the audience that his protagonist was an exceptional man, worthy of admiration and sympathy. Antony says, "This was the noblest Roman of them all." Furthermore, Antony adds that Nature herself should tell the world, "This was a man."