| Millennium: | 1st millennium |
|---|---|
| Centuries: | |
| Decades: | |
| Years: |
| 866 by topic |
|---|
| Leaders |
| Categories |
| Gregorian calendar | 866 DCCCLXVI |
| Ab urbe condita | 1619 |
| Armenian calendar | 315 ԹՎ ՅԺԵ |
| Assyrian calendar | 5616 |
| Balinese saka calendar | 787–788 |
| Bengali calendar | 273 |
| Berber calendar | 1816 |
| Buddhist calendar | 1410 |
| Burmese calendar | 228 |
| Byzantine calendar | 6374–6375 |
| Chinese calendar | 乙酉年 (Wood Rooster) 3563 or 3356 — to — 丙戌年 (Fire Dog) 3564 or 3357 |
| Coptic calendar | 582–583 |
| Discordian calendar | 2032 |
| Ethiopian calendar | 858–859 |
| Hebrew calendar | 4626–4627 |
| Hindu calendars | |
| - Vikram Samvat | 922–923 |
| - Shaka Samvat | 787–788 |
| - Kali Yuga | 3966–3967 |
| Holocene calendar | 10866 |
| Iranian calendar | 244–245 |
| Islamic calendar | 251–252 |
| Japanese calendar | Jōgan 8 (貞観８年) |
| Javanese calendar | 763–764 |
| Julian calendar | 866 DCCCLXVI |
| Korean calendar | 3199 |
| Minguo calendar | 1046 before ROC 民前1046年 |
| Nanakshahi calendar | −602 |
| Seleucid era | 1177/1178 AG |
| Thai solar calendar | 1408–1409 |
| Tibetan calendar | 阴木鸡年 (female Wood-Rooster) 992 or 611 or −161 — to — 阳火狗年 (male Fire-Dog) 993 or 612 or −160 |
Year 866 (DCCCLXVI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar.