40s BC
{{Short description|Decade}}
{{image frame|content={{Photomontage
| photo1a = Caesar-ueberschreitet-den-rubikon.jpg
| photo1b = Incendie Alexandrie by Hermann Goll 1876.jpg
| photo2a = Caesar-07.jpg
| photo2b = Death of Julius Caesar 2.png
| size = 400
| text = From left, clockwise: Julius Caesar crossing the Rubicon; Fire of Alexandria following a Roman siege; Assassination of Pompey the Great; Assassination of Julius Caesar.
}}}}
{{Decadebox BC|4}}
This article concerns the period 49 BC – 40 BC.
{{Events by year for decade BC|4}}
Significant people
- Julius Caesar, Roman dictator (lived 100–44 BC, term 46–44 BC)
- Marcus Junius Brutus, Roman politician (85–42 BC)
- Mark Antony, Roman politician and general (83–30 BC)
- Pharaoh Cleopatra VII of Egypt (lived 70/69–30 BC, reigned 51–30 BC)—enters her twenties, has son Caesarion with Julius Caesar, before meeting Mark Antony
- Gaius Iulius Caesar Octavianus, Roman politician and general (62 BC–AD 14)
- Pharaoh Ptolemy XV Caesarion (lived 47–30 BC, reigned 44–30 BC)
- Gaius Cassius Longinus, Roman politician (died 42 BC)
{{Births and deaths by year for decade|-4}}