820
| Years: 816 817 818 819 – 820 – 821 822 823 824 | |
| Decades: 790s 800s 810s – 820s – 830s 840s 850s | |
| Centuries: 8th century – 9th century – 10th century | |
Events
- Michael II succeeds Leo V as Byzantine Emperor
- The Historia Brittonum is written (approximate date)
Births
- Rhodri Mawr ('the Great'), ruler of Gwynedd (Wales) (approximate date) (d. 878)
- Photius I, Patriarch of Constantinople (approximate date) (d. 891)
Deaths
- December 24 – Leo V, Byzantine Emperor (b. 775)(assassinated)
- Tang Xian Zong, emperor of China (end of reign)
Categories: 820