December 26 - Dion Boucicault, Irish actor and playwright (d. 1890)
May 17 - Armand-Emmanuel du Plessis, Duc de Richelieu
June 25 - E.T.A. Hoffmann, German writer (b. 1776)
July 2 - Denmark Vesey, American who planned slave revolt
July 8 - Percy Bysshe Shelley, English poet (b. 1792)
September 11 - Fortunat Alojzy Gonzaga Żółkowski, Polish actor (b. 1777)
October 16 - Eva Marie Veigel, Austrian ballet dancer (b. 1724)
January 9 - The Portuguese prince Pedro I of Brazil decides to stay in Brazil against the orders of the Portuguese king João VI, starting the Brazilian independence process.
January 13 - The design of the Greek flag is adopted by the First National Assembly at Epidaurus.
January 14 - Greek War of Independence: Acrocorinth is captured by Theodoros Kolokotronis and Demetrius Ypsilanti.
January 15 - Greek War of Independence: Demetrius Ypsilanti is elected president of the legislative assembly.
February 9 - Haiti invades the newly founded Dominican Republic.
February 24 - The 1st Swaminarayan temple in the world, Shri Swaminarayan Mandir, Ahmedabad was inaugurated.
March 30 - Florida Territory created in the United States.
March 31 - The massacre of the population of the Greek island of Chios by soldiers of the Ottoman Empire following a rebellion attempt, depicted by the French artist Eugène Delacroix.
May 16 - Greek War of Independence: The Turks capture the Greek town of Souli.
May 24 - Battle of Pichincha: Antonio José de Sucre secures the independence of the Presidency of Quito.
June 14 - Charles Babbage proposes a difference engine in a paper to the Royal Astronomical Society entitled "Note on the application of machinery to the computation of astronomical and mathematical tables".
July 8 - Chippewas turn over huge tract of land in Ontario to the United Kingdom.
July 26 - José de San Martín arrives in Guayaquil, Ecuador, to meet with Simón Bolívar.
September 7 - Dom Pedro I declares Brazil independent from Portugal on the shores of the Ipiranga river in São Paulo.
September 27 - Jean-François Champollion announces that he has deciphered the Rosetta stone.
October 19 - In Parnaíba; Simplício Dias da Silva, João Cândido de Deus e Silva and Domingos Dias declare the independent state of Piauí.