821

Millennium:	1st millennium
Centuries:	8th century – 9th century – 10th century
Decades:	790s 800s 810s – 820s – 830s 840s 850s
Years:	818 819 820 – 821 – 822 823 824

821 by topic
Politics
State leaders – Sovereign states
Birth and death categories
Births – Deaths
Establishment and disestablishment categories
Establishments – Disestablishments

821 in other calendars
Gregorian calendar	821 DCCCXXI
Ab urbe condita	1574
Armenian calendar	270 ԹՎ ՄՀ
Assyrian calendar	5571
Bengali calendar	228
Berber calendar	1771
Buddhist calendar	1365
Burmese calendar	183
Byzantine calendar	6329–6330
Chinese calendar	庚子年 (Metal Rat) 3517 or 3457 — to — 辛丑年 (Metal Ox) 3518 or 3458
Coptic calendar	537–538
Discordian calendar	1987
Ethiopian calendar	813–814
Hebrew calendar	4581–4582
Hindu calendars
- Vikram Samvat	877–878
- Shaka Samvat	743–744
- Kali Yuga	3922–3923
Holocene calendar	10821
Iranian calendar	199–200
Islamic calendar	205–206
Japanese calendar	Kōnin 12 (弘仁１２年)
Julian calendar	821 DCCCXXI
Korean calendar	3154
Minguo calendar	1091 before ROC 民前1091年
Seleucid era	1132/1133 AG
Thai solar calendar	1363–1364

Wikimedia Commons has media related to 821.

Year 821 (DCCCXXI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar.

Events

The Byzantine general Thomas the Slav secures control over most of Byzantine Anatolia as well as recognition from the Abbasid Caliphate, and crosses over into Europe. The emperor Michael II is blockaded in Constantinople, but Thomas' first attack on the city fails.