| Millennium: | 1st millennium |
|---|---|
| Centuries: | 4th century – 5th century – 6th century |
| Decades: | 420s 430s 440s – 450s – 460s 470s 480s |
| Years: | 448 449 450 – 451 – 452 453 454 |
| 451 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 451 CDLI |
| Ab urbe condita | 1204 |
| Armenian calendar | N/A |
| Assyrian calendar | 5201 |
| Bahá'í calendar | -1393–-1392 |
| Bengali calendar | -142 |
| Berber calendar | 1401 |
| English Regnal year | N/A |
| Buddhist calendar | 995 |
| Burmese calendar | -187 |
| Byzantine calendar | 5959–5960 |
| Chinese calendar | 庚寅年十一月十三日 (3087/3147-11-13) — to —
辛卯年十一月廿三日(3088/3148-11-23) |
| Coptic calendar | 167–168 |
| Ethiopian calendar | 443–444 |
| Hebrew calendar | 4211–4212 |
| Hindu calendars | |
| - Vikram Samvat | 507–508 |
| - Shaka Samvat | 373–374 |
| - Kali Yuga | 3552–3553 |
| Holocene calendar | 10451 |
| Iranian calendar | 171 BP – 170 BP |
| Islamic calendar | 176 BH – 175 BH |
| Japanese calendar | |
| Korean calendar | 2784 |
| Minguo calendar | 1461 before ROC 民前1461年 |
| Thai solar calendar | 994 |
Year 451 (CDLI) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Marcianus and Adelfius (or, less frequently, year 1204 Ab urbe condita). The denomination 451 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.