| Millennium: | 1st millennium |
|---|---|
| Centuries: | 1st century – 2nd century – 3rd century |
| Decades: | 90s 100s 110s – 120s – 130s 140s 150s |
| Years: | 118 119 120 – 121 – 122 123 124 |
| 121 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 121 CXXI |
| Ab urbe condita | 874 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1723 – -1722 |
| Bengali calendar | -472 |
| Berber calendar | 1071 |
| Buddhist calendar | 665 |
| Burmese calendar | -517 |
| Byzantine calendar | 5629 – 5630 |
| Chinese calendar | 庚申年十一月廿五日 (2757/2817-11-25) — to —
辛酉年十二月初五日(2758/2818-12-5) |
| Coptic calendar | -163 – -162 |
| Ethiopian calendar | 113 – 114 |
| Hebrew calendar | 3881 – 3882 |
| Hindu calendars | |
| - Bikram Samwat | 177 – 178 |
| - Shaka Samvat | 43 – 44 |
| - Kali Yuga | 3222 – 3223 |
| Holocene calendar | 10121 |
| Iranian calendar | 501 BP – 500 BP |
| Islamic calendar | 516 BH – 515 BH |
| Japanese calendar | |
| Korean calendar | 2454 |
| Thai solar calendar | 664 |
Year 121 (CXXI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar.