|French Republican calendar||9–10|
|Ab urbe condita||2554|
|Balinese saka calendar||1722–1723|
|British Regnal year||41 Geo. 3 – 42 Geo. 3|
|Chinese calendar||庚申年 (Metal Monkey)|
4497 or 4437
— to —
辛酉年 (Metal Rooster)
4498 or 4438
|- Vikram Samvat||1857–1858|
|- Shaka Samvat||1722–1723|
|- Kali Yuga||4901–4902|
|Japanese calendar||Kansei 13|
|Julian calendar||Gregorian minus 12 days|
|Minguo calendar||111 before ROC|
|Thai solar calendar||2343–2344|
1927 or 1546 or 774
— to —
1928 or 1547 or 775
|Wikimedia Commons has media related to 1801.|
1801 (MDCCCI) was a common year starting on Thursday of the Gregorian calendar and a common year starting on Tuesday of the Julian calendar, the 1801st year of the Common Era (CE) and Anno Domini (AD) designations, the 801st year of the 2nd millennium, the 1st year of the 19th century, and the 2nd year of the 1800s decade. As of the start of 1801, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.
- January 1
- January 3 – Toussaint Louverture triumphantly enters Santo Domingo, the capital of the former Spanish colony of Santo Domingo, which has become a colony of Napoleonic France.
- January 31 – John Marshall is appointed Chief Justice of the United States.
- February 4 – William Pitt the Younger resigns as Prime Minister of the United Kingdom.
- February 9 – The Treaty of Lunéville ends the War of the Second Coalition between France and Austria. Under the terms of the treaty, Aachen is officially annexed by France.
- February 17 – An electoral tie between Thomas Jefferson and Aaron Burr is resolved, when Jefferson is elected President of the United States and Burr Vice President by the United States House of Representatives.
- February 27 – Washington, D.C. is placed under the jurisdiction of the United States Congress.
- March 4 – Thomas Jefferson is sworn in as the third President of the United States.
- March 10 – The first census is held in Great Britain. The population of England and Wales is determined to be 8.9 million, with London revealed to have 860,035 residents. 1.5 million people live in cities of 20,000 or more in England and Wales, accounting for 17% of the total English population.
- March 14 – Henry Addington becomes First Lord of the Treasury and Chancellor of the Exchequer, effectively Prime Minister of the United Kingdom.
- March 21 – Battle of Alexandria in Egypt: British troops defeat the French, but the British commander, Sir Ralph Abercromby, dies later of a wound received in the action.
- March 23 – Tsar Paul I of Russia is murdered; he is succeeded by his son Alexander I.
- April 2 – War of the Second Coalition – First Battle of Copenhagen: The British Royal Navy, under Admiral Sir Hyde Parker, forces the Royal Dano-Norwegian Navy to accept an armistice. Vice-Admiral Horatio Nelson leads the main attack, deliberately disregarding his commander's signal to withdraw. He is created a Viscount on May 19; Denmark-Norway is forced to withdraw from the Second League of Armed Neutrality.
- April 21 – Ranjit Singh is invested, as Maharaja of Punjab.
- May 6 – French Revolutionary Wars – Action of 6 May 1801 off Barcelona: British Royal Navy brig HMS Speedy, although outmanned and outgunned, captures 32-gun Spanish frigate El Gamo.
- May 10 – The pascha of Tripoli declares war on the United States, by having the flagpole on the consulate chopped down.
- June 7 – War of the Oranges ends: Portugal and Spain sign the Treaty of Badajoz; Portugal loses the city of Olivenza.
- June 15 – A bull breaks through barriers at a bullfight in Madrid, killing two people (including the mayor of Torrejón de Ardoz). and injuring a number of other spectators.
- June 27 – Siege of Cairo ends: Cairo falls to British troops.
- July 6 – Battle of Algeciras: The French fleet defeats the British fleet.
- July 7 – Toussaint Louverture promulgates a reforming constitution for Santo Domingo, declaring himself emperor for life of the entire island of Hispaniola, and nominally abolishing slavery.
- July 12 – Second Battle of Algeciras: The British fleet defeats the French and Spanish fleets.
- July 18 – Napoleon signs a Concordat with Pope Pius VII.
- August 1 – First Barbary War – Action of 1 August 1801: United States Navy schooner USS Enterprise (1799) captures 14-gun Tripolitan corsair polacca Tripoli off the north African coast, in a single-ship action.
- September 9 – Alexander I of Russia confirms the privileges of the Baltic provinces.
- September 24 – Joseph Marie Jacquard exhibits his new invention, a loom where the pattern being woven is controlled by punched cards, at the National Exposition in Paris.
- September 30 – The Treaty of London is signed for preliminary peace between the French First Republic and the United Kingdom of Great Britain and Ireland.
- October 17 – A coup d'état is staged in the Batavian Republic.
- November 16 – The first edition of the New-York Evening Post is printed.
- December 15 – Hadži Mustafa Pasha, Ottoman commander and politician, is assassinated in Belgrade, Sanjak of Smederevo by Kučuk-Alija.
- December 19 – South Carolina College, a precursor to The University of South Carolina, is established in Columbia, South Carolina.
- 24 December – Cornish engineers Richard Trevithick and Andrew Vivian demonstrated Puffing Devil, their steam-powered road locomotive, in Camborne. The trial was successful but Trevithick realised the limitations of steam power in a road-running vehicle and turned his attention to rail, introducing the world's first steam railway locomotive in 1804.
- The first census is held in France.
- Philippe Pinel publishes Traité médico-philosophique sur l'aliénation mentale; ou la manie, presenting his enlightened humane psychological approach to the management of psychiatric hospitals. Translated into English by D. D. Davis as Treatise on Insanity in 1806, it is influential on both sides of the Atlantic during the nineteenth century.
- Ultraviolet radiation is discovered by Johann Wilhelm Ritter.
- The magnum opus Disquisitiones Arithmeticae of Carl Friedrich Gauss is published.
- The Supreme Council, Scottish Rite (Southern Jurisdiction, USA) is founded within Freemasonry.
- January 3 – Gijsbert Haan, Dutch-American religious leader (d. 1874)
- January 11 – Honório Hermeto Carneiro Leão, Marquis of Paraná, Brazilian politician (d. 1856)
- January 14 – Jane Welsh Carlyle, wife of Scottish essayist Thomas Carlyle (d. 1866)
- February 1
- February 13 – János Kardos, Hungarian Slovenes evangelical priest, teacher and writer (d. 1875)
- February 21 – John Henry Newman, English Catholic Cardinal (d. 1890)
- May 5 – Pío Pico, last Governor of Alta California (d. 1894)
- May 9 – Peter Hesketh-Fleetwood, English Member of Parliament, developer (d. 1866)
- May 11 – Henri Labrouste, French architect (d. 1875)
- May 16 – William H. Seward, 24th United States Secretary of State (d. 1872)
- May 17 – Lovisa Åhrberg, first woman doctor, surgeon in Sweden (d. 1881)
- May 31 – Johann Georg Baiter, Swiss philologist, textual critic (d. 1877)
- June 1 – Brigham Young, American Mormon leader, colonizer (d. 1877)
- June 5 – William Scamp, English architect and engineer (d. 1872)
- June 4 – James Pennethorne, English architect (d. 1871)
- June 14 – Heber C. Kimball, American religious leader (d. 1868)
- June 16 – Julius Plücker, German mathematician, physicist (d. 1868)
- June 24 – Caroline Clive, English writer (d. 1873)
- June 30 – Frédéric Bastiat, French philosopher (d. 1850)
- July 5 – David Farragut, American admiral (d. 1870)
- July 14 – Johannes Peter Müller, German physiologist, comparative anatomist, ichthyologist, and herpetologist (d. 1858)
- July 27 – George Biddell Airy, English mathematician, astronomer (d. 1892)
- September 1 – Hortense Allart, French writer (d. 1879)
- September 3 – Christian Erich Hermann von Meyer, German palaeontologist (d. 1869)
- October 12
- October 23 – Albert Lortzing, German composer (d. 1851)
- November 3
- November 10 – Vladimir Dal, Russian lexicographer (d. 1872)
- November 13 – Queen Elisabeth Ludovika of Bavaria, queen of Prussia (d. 1873)
- December 11 – Christian Dietrich Grabbe, German writer (d. 1836)
- Dai Xi, Chinese painter (d. 1860)
- Franciszek Ksawery Godebski, Polish writer (d. 1869)
- Thierry Hermès, German-born French businessman, founder of Hermès (d. 1878)
- Brita Sofia Hesselius, Swedish photographer (d. 1866)
- Cynthia Taggart, American poet (d. 1849)
- January 2 – Johann Kaspar Lavater, Swiss physiognomist (b. 1741)
- January 11 – Domenico Cimarosa, Italian composer (b. 1749)
- February 7 – Daniel Chodowiecki, Polish painter (b. 1726)
- February 17 – Princess Philippine Charlotte of Prussia (b. 1716)
- March 14 – Margarita "Peggy" Schuyler Van Rensselaer, American socialite, Angelica Schuyler Church's sister (b. 1758)
- March 19 – Ambrosio O'Higgins, 1st Marquis of Osorno, Spanish viceroy of Peru and Governor of the Captaincy General of Chile, father of Bernardo O'Higgins
- March 21 – Andrea Luchesi, Italian composer (b. 1741)
- March 23 – Tsar Paul I of Russia (b. 1754)
- March 25 – Novalis, German poet (b. 1772)
- March 28 – Ralph Abercromby, British general (b. 1734)
- April 2 – Thomas Dadford, Jr., British engineer
- April 7 – Noël François de Wailly, French lexicographer (b. 1724)
- May 3 – Cyrus Trapaud, British Army general (b. 1715)
- May 17 – William Heberden, English physician (b. 1710)
- June 4 – Frederick Muhlenberg, first Speaker of the U.S. House of Representatives (b. 1750)
- June 14 – Benedict Arnold, American Revolution hero, then traitor (b. 1741)
- July 4 – Leendert Viervant the Younger, Dutch architect (b. 1752)
- August 13 – George Gordon, 3rd Earl of Aberdeen (b. 1722)
- August 31 – Nicola Sala, Italian opera composer (b. 1713)
- September 19 – Johann Gottfried Koehler, German astronomer (b. 1745)
- October 3 – Philippe Henri, marquis de Ségur, Marshal of France (b. 1724)
- November 4 – William Shippen, American physician, Continental Congressman (b. 1712)
- November 5
- November 24
- "Chronology of State Medicine". Archived from the original on August 9, 2007. Retrieved August 10, 2007.
- Everett, Jason M., ed. (2006). "1801". The People's Chronology. Thomson Gale.
- "Dreadful events in the front rows of the ring at Madrid and the death of the mayor of Torrejón, Plate 21 of La Tauromaquia". National Galleries of Scotland. Retrieved on 25 February 2010.
- Michael P. Fitzsimmons, From Artisan to Worker: Guilds, the French State, and the Organization of Labor, 1776-1821 (Cambridge University Press, 2010) p132
- British Steam. Igloo Books. 2016. pp. 10–13.
- Foucault, Michel (1961). Folie et déraison: histoire de la folie à l'âge classique.
- Hughes, Quentin; Thake, Conrad (2005). Malta, War & Peace: An Architectural Chronicle 1800–2000. Midsea Books Ltd. p. 250. ISBN 9789993270553.