Who is the tragic hero of Shakespeare's Julius Caesar?

The tragic hero of William Shakespeare's Julius Caesar is Brutus. Brutus is the character who most fulfills Aristotle's definition of a tragic hero.

First, he is a noble character, of high station, whose actions have a certain grandeur. He is morally admirable; Anthony states of him that he is "the noblest Roman of them all." Rather than being motivated by jealousy or love for power or personal gain, as the other conspirators, Brutus is an idealist, who acts solely from the patriotic desire to restore the Republic. 

The main flaw of Brutus as a character is poor judgment. He lacks the common touch and as a speaker is honest and rational rather than manipulative. His dedication to his ideals lead him to kill Caesar, a man whom he genuinely likes and admires. He also trusts the other conspirators to much, rather than realizing that their motives are less pure than his own.