866
| 866 in altris calendaris | |
| Calendari gregorian | 866 |
| Ab urbe condita | 1619 |
| Calendari armen | 315 |
| Calendari cinês | 3562 — 3563 |
| Calendari ebraic | 4625 — 4626 |
| Calendari hindu - Vikram Samvat - Shaka Samvat - Kali Yuga |
921 — 922 788 — 789 3967 — 3968 |
| Calendari iranian | 244 — 245 |
| Calendari islamic | 286 — 287 |
| Calendari runic | 1116 |