Publius Volumnius was a 1st-century BC Roman philosopher, and a friend and companion of Marcus Junius Brutus who led the conspiracy to assassinate Julius Caesar. Volumnius and Brutus had been students of philosophy together. Volumnius accompanied Brutus on his fateful campaign to the East, which culminated in Brutus' suicide after his defeat by the Triumvirs in the Second Battle of Philippi (October 23, 42 BC). The well-known quote by Brutus calling down a curse upon Mark Antony was also taken from the memoirs of Volumnius: Volumnius appears as a character in Shakespeare's play Julius Caesar.