|Millennium:||1st millennium BC|
|Centuries:||2nd century BC – 1st century BC – 1st century|
|Decades:||80s BC 70s BC 60s BC – 50s BC – 40s BC 30s BC 20s BC|
|Years:||59 BC 58 BC 57 BC – 56 BC – 55 BC 54 BC 53 BC|
|56 BC by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishments and disestablishments categories|
|Establishments – Disestablishments|
|Gregorian calendar||56 BC|
|Ab urbe condita||698|
|Bahá'í calendar||−1899 – −1898|
|English Regnal year||N/A|
|Chinese calendar||甲子年 (Wood Rat)
2641 or 2581
— to —
乙丑年 (Wood Ox)
2642 or 2582
|Coptic calendar||−339 – −338|
|Ethiopian calendar||−63 – −62|
|- Vikram Samvat||1–2|
|- Shaka Samvat||N/A|
|- Kali Yuga||3046–3047|
|Igbo calendar||−1055 – −1054|
|Iranian calendar||677 BP – 676 BP|
|Islamic calendar||698 BH – 697 BH|
|Minguo calendar||1967 before ROC
|Thai solar calendar||488|
|Wikimedia Commons has media related to 56 BC.|
Year 56 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Lentulus and Philippus (or, less frequently, year 698 Ab urbe condita). The denomination 56 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- This year, or possibly the following year, the king of the Trinovantes, possibly called Imanuentius, is overthrown and killed by his rival Cassivellaunus. His son Mandubracius flees to Gaul and appeals to Julius Caesar for help.
- Consuls: Gnaeus Cornelius Lentulus Marcellinus and Lucius Marcius Philippus.
- Clodia accuses her former lover Marcus Caelius Rufus of trying to poison her. The trial ends with the defendant acquitted thanks to the Pro Caelio speech of Marcus Tullius Cicero. There is no further mention of the previously famous Clodia.
- Gallic War: Decimus Junius Brutus Albinus defeats the Veneti of Brittany: The Gallics lost most of their swanships to the Romans at the battle in modern-day Quiberon Bay. The strongholds on the coast are stormed and the population is slaughtered or sold into slavery.