- End of Roman Republic period and establishment of Roman Empire.
- March 15 – Ides of March: Julius Caesar, dictator of Rome, is assassinated by a group of Roman senators.
- April 18 – Octavian arrives in Naples from Greece to take up the inheritance of Julius Caesar.
- June – Mark Antony granted a five-year governorship of northern and central Transalpine Gaul (France) and Cisalpine Gaul (Northern Italy).
- September 2 – Pharaoh Cleopatra VII of Egypt declares her son co-ruler as Ptolemy XV Caesarion.
- September 2 – First of Cicero’s Philippics (oratorical attacks) on Antony. He will make 14 of them over the next several months.
- Comosicus succeeds Burebista as king of Dacia.