| 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: | 54 BC 53 BC 52 BC - 51 BC - 50 BC 49 BC 48 BC |
| 51 BC by topic | |
| Politics | |
| State leaders - Sovereign states | |
| Birth and death categories | |
| Births - Deaths | |
| Establishments and disestablishments categories | |
| - | |
| Gregorian calendar | 51 BC |
| Ab urbe condita | 703 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1894 – -1893 |
| Berber calendar | 900 |
| Buddhist calendar | 494 |
| Burmese calendar | -688 |
| Chinese calendar | 2586/2646 (己巳年) — to —
2587/2647(庚午年) |
| Coptic calendar | -334 – -333 |
| Ethiopian calendar | -58 – -57 |
| Hebrew calendar | 3710 – 3711 |
| Hindu calendars | |
| - Vikram Samvat | 5 – 6 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 3051 – 3052 |
| Holocene calendar | 9950 |
| Iranian calendar | 672 BP – 671 BP |
| Islamic calendar | 693 BH – 692 BH |
| Japanese calendar | |
| - Imperial Year | Kōki 610 (皇紀610年) |
| Julian calendar | -5 |
| Korean calendar | 2283 |
| Thai solar calendar | 493 |
Events
By place
Rome
- Consuls: Marcus Claudius Marcellus and Servius Sulpicius Rufus.
- Pompey demands that Julius Caesar lay down his command before he can stand for consul.
Egypt
- Spring — Pharaoh Ptolemy XII dies and is succeeded by his eldest surviving daughter Cleopatra VII and her younger brother and co-ruler Ptolemy XIII.
Asia
Births
- Publius Sulpicius Quirinius, Roman governor of Syria
- Cheng, Emperor of the Han Dynasty of China
Deaths
- Spring — Pharaoh Ptolemy XII of Egypt
- Posidonius of Apamea, Greek philosopher, astronomer, geographer
