|Centuries:||18th century – 19th century – 20th century|
|Decades:||1780s 1790s 1800s – 1810s – 1820s 1830s 1840s|
|Years:||1808 1809 1810 – 1811 – 1812 1813 1814|
Year 1811 (MDCCCXI) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Sunday of the 12-day slower Julian calendar).
|Ab urbe condita||2564|
|British Regnal year||51 Geo. 3 – 52 Geo. 3|
|Chinese calendar|| 庚午年十二月初七日
— to —辛未年十一月十六日
|- Vikram Samvat||1867–1868|
|- Shaka Samvat||1733–1734|
|- Kali Yuga||4912–4913|
|- Ǹrí Ìgbò||811–812|
|Japanese calendar|| Bunka 8
|Juche calendar||N/A (before 1912)|
|Julian calendar||Gregorian minus 12 days|
|Minguo calendar||101 before ROC
|Thai solar calendar||2354|
Events of 1811
January - March
- January 3 - Unsuccessful slave revolt led by Charles Deslandes in St. Charles and St. James, Louisiana.
- January 22 - Beginning of " Casas Revolt", San Antonio, Texas.
- February 5 - George, Prince of Wales becomes Regent because of the perceived insanity of his father, King George III of the United Kingdom. He is known as the Prince Regent. This is the beginning of the Regency period.
- March 1 - Egyptian ruler Mohammed Ali kills the last Mamluk leaders in the Citadel Massacre.
- March 13 - Battle of Lissa (1811) - British fleet defeats the French one.
- March 25 - The Great Comet of 1811 is discovered by Honouré Flaugergues.
- March 27 - Battle of Anholt: British naval victory over Denmark.
April - June
- April 5- April 6 - Revolutionary riots in Buenos Aires.
- May 14 - Paraguay declares independence from Spain.
- May 16 - Battle of Albuera.
- June 9 - Great fire of the Podil
July - September
- July 5 - Venezuela declares its independence from Spain.
- July 11 - Italian scientist Amedeo Avogadro publishes his memoire about molecular content of gases.
- September - First annual Rosh Hashana kibbutz (pilgrimage) of Breslov Hasidim to the grave of Rabbi Nachman of Breslov in Uman, Ukraine, led by Nathan of Breslov.
October - December
- October 11 - Inventor John Stevens' boat, the Juliana, begins operation as the first steam-powered ferry (service between New York, New York, and Hoboken, New Jersey).
- November - Luddite uprisings begin in northern England and Midlands.
- November 6 - Battle of Tippecanoe.
- December 16 - Earthquake in Mississippi Valley near New Madrid reverses the course of the river for a while. Other earthquakes along the fault occur on January 23, 1812 and February 7, 1812.
- Argentine War of Independence 1810-1818
- Black War 1804-1835
- Bolivian Independence War 1809-1824
- Gunboat War 1807-1814
- Mtetwa Empire expansion
- Napoleonic Wars (1799-1815) - Peninsular War
- Russo-Persian War (1804-1813)
- Russo-Turkish War, 1806-1812
January - June
- January 9 - Gilbert Abbott à Beckett, English writer (d. 1856)
- January 17 - Joshua Abraham Norton, self-declared Emperor Norton I of the United States (d. 1880)
- February 3 - Horace Greeley, American journalist, editor, and publisher (d. 1872)
- February 6 - Henry George Liddell, English clergyman (d. 1898)
- March 20 - Napoleon II of France (d. 1832)
- March 21 - Nathaniel Woodard, English eeducationalist (d. 1891)
- March 30 - Robert Bunsen, German chemist and inventor (d. 1899)
- May 11
- Chang and Eng Bunker, siamese twins and sideshow performers.
- Jean-Jacques Challet-Venel, member of the Swiss Federal Council (d. 1893)
- June 14 - Harriet Beecher Stowe, American author (d. 1896)
July - December
- July 18 - William Makepeace Thackeray, British novelist (d. 1863)
- August 31 - Theophile Gautier, French writer (d. 1872)
- September 19 - Orson Pratt, American religious leader (d. 1881)
- October 22 - Franz Liszt, Hungarian composer and pianist (d. 1886)
- October 25 - Évariste Galois, French mathematician (d. 1832)
- October 27 - Stevens Thomson Mason, first governor of Michigan (d. 1843)
- November 21
- November 24 - Ulrich Ochsenbein, Swiss Federal Councilor (d. 1890)
- December 21 - Archibald Campbell Tait, Archbishop of Canterbury (d. 1882)
- date unknown - Mohammad Afzal Khan, Emir of Kabul, Emir of Kandahar (d. 1867)
January - June
- January 10 - Marie-Joseph Chénier, French poet (b. 1764)
- February 26 - Mateo de Toro Zambrano y Ureta, Governor of Chile (b. 1727)
- March 14 - Augustus FitzRoy, 3rd Duke of Grafton, Prime Minister of the United Kingdom (b. 1735)
- April 7 - Garsevan Chavchavadze, Georgian diplomat and politician (b. 1757)
- May 4 - Nikolay Kamensky, Russian general (b. 1776)
- May 28 - Henry Dundas, 1st Viscount Melville, British minister (b. 1742)
- June 26 - Ignacio Allende, captain of the Spanish Army in Mexico
July - December
- July 30 - Miguel Hidalgo y Costilla, Mexican revolutionary (b. 1753)
- August - William Williams, Signer of the Declaration of Independence (b. 1731)
- August 20 - Louis Antoine de Bougainville, French navigator and military commander (b. 1729)
- September - Ulrich Jasper Seetzen, explorer (b. 1767)
- September 8 - Peter Simon Pallas, German zoologist (b. 1741)
- October 11 - Johann Conrad Ammann, Swiss physician and naturalist (b. 1724)
- November 18 - Adam Weishaupt, German founder of the Illuminati (b. 1748)
- November 21 - Heinrich von Kleist, German writer (suicide) (b. 1777)
- November 27 - Andrew Meikle, English engineer (b. 1719)