866
| Years: 862 863 864 865 - 866 - 867 868 869 870 | |
| Decades: 830s 840s 850s - 860s - 870s 880s 890s | |
| Centuries: 8th century - 9th century - 10th century | |
- Fujiwara no Yoshifusa becomes regent of Japan, starting the Fujiwara regentship.
- Alfonso III succeeds as king of Asturias.
- Louis II beats the Saracen invaders in Italy.
- Ivar the Boneless crosses over to England and beats and captures king Ella of Northumbria, thus revenging his father Ragnar Lodbrok.
- Ethelred succeeds as king of Wessex (or 865).
- Pope Nicholas I forbids the use of torture in prosecutions for witchcraft.
- A "great Viking army" captured York
Deaths