857
| Years: 853 854 855 856 - 857 - 858 859 860 861 | |
| Decades: 820s 830s 840s - 850s - 860s 870s 880s | |
| Centuries: 8th century - 9th century - 10th century | |
Events
- Viking raid of Dorestad.
- Michael III of Byzantium, under influences of his uncle Bardas, banishes his mother Theodora. Bardas becomes the most powerful person in the empire.
Deaths
- February 4 - Rabanus Maurus, abbot of Fulda, theologian