In William Shakespeare’s Julius Caesar, written in about 1599 and first performed in September of that same year, Shakespeare identifies eight of the more than sixty historical conspirators against Caesar as Marcus Brutus, Cassius, Casca, Trebonius, Ligarius, Decius Brutus, Metellus Cimber, and Cinna. Historically, all of these men were likely involved in the actual assassination of Caesar, except for Trebonius and Cinna.
Trebonius was assigned the task of distracting Mark Antony while the conspirators attacked Caesar.
CASSIUS. Trebonius knows his time; for, look you, Brutus.
He draws Mark Antony out of the way.
Exeunt ANTONY and TREBONIUS. (3.1.29–30)
Cinna is reported to have given a passionate speech in support of the conspirators in the first meeting of the Senate after the assassination, but Shakespeare alters history to put Cinna at the scene of the assassination.
Before the assassination, Cinna tells Casca “you are the first that rears your hand” (3.1.34), and Cinna is the first to speak after Caesar dies.
CINNA. Liberty! Freedom! Tyranny is dead!
Run hence, proclaim, cry it about the streets. (3.1.86–87)
As noted above, Cinna assigns the first attack against Caesar to Casca, and Casca initiates the attack with his line, “Speak, hands, for me!” (3.1.84).
It is somewhat unclear, depending perhaps on the version one reads, if Casca’s line indicates that he’s the first to stab Caesar or if he’s simply one of many “hands” who attack Caesar at the same time, since the stage direction, at least in some versions, directly following Casca’s line is “They stab Caesar.”
The stage directions also indicate that the final blow against Caesar is struck by Brutus, following Caesar’s famous remark, “Et tu, Brute?” (3.1.85).
It’s impossible to know, and Shakespeare gives no clear indication of, the actual order of stabbing blows to Caesar’s body, nor is it possible to know the number and names of the actual assassins.
A physician named Antistius, possibly Caesar's personal physician, examined Caesar’s body after the assassination. Antistius reported that he found twenty-three stab wounds on Caesar's body, only one of which—one of two wounds near the heart—would have proved fatal. Antistius concluded that Caesar’s death would not have been instantaneous, but that Caesar likely died from internal bleeding as a result of that single wound.
Modern interpretations of Antistius’s report and other historical records suggest that, based on the number of stab wounds, the assassination was carried out by five to ten assassins, possibly including those named by Shakespeare in Julius Caesar.