Brutus

Marcus Junius
[joon-yuh s] /ˈdʒun yəs/ (Show IPA), 85?–42 b.c, Roman provincial administrator: one of the assassins of Julius Caesar.
and thou, Brutus!: alleged dying words of Julius Caesar uttered as his friend Brutus stabbed him.
Contemporary Examples

Danger Stalks Lucas Davenport Daily Beast Promotions May 10, 2009
Erasing Dan Rather Lloyd Grove September 15, 2009
Lights, Camera, Cocktails Brody Brown July 7, 2011
War’s Most Powerful Weapon: Double Agents from WWII to Al Qaeda Ben Macintyre July 27, 2012

Historical Examples

Shakespeare and Music Edward W. Naylor
The Man Shakespeare Frank Harris
Five Hundred Mistakes of Daily Occurrence in Speaking, Pronouncing, and Writing the English Language, Corrected Anonymous
The Man Shakespeare Frank Harris
Shakespeare as a Dramatic Artist Richard G. Moulton
The Trampling of the Lilies Rafael Sabatini

noun
Lucius Junius (ˈluːʃəs ˈdʒuːnɪəs). late 6th century bc, Roman statesman who ousted the tyrant Tarquin (509) and helped found the Roman republic
Marcus Junius (ˈmɑːkəs ˈdʒuːnɪəs) ?85–42 bc, Roman statesman who, with Cassius, led the conspiracy to assassinate Caesar (44): committed suicide after being defeated by Antony and Octavian (Augustus) at Philippi (42)

Note: Brutus is a leading character in the play Julius Caesar, by William Shakespeare.

Note: Caesar is said to have addressed Brutus with the words Et tu, Brute? (“Even you, Brutus?”) as Brutus stabbed him. This sentence has become a proverbial response to betrayal.