* 1821 – Ford Madox Brown, English painter ( d. 1893 )

* 1769 – Napoleon, Corsican-French military officer and political leader ( d. 1821 )

* 1821 – Jarvis Island is discovered by the crew of the ship, Eliza Frances.

* 1821 – The Treaty of Córdoba is signed in Córdoba, now in Veracruz, Mexico, concluding the Mexican War of Independence from Spain.

* 1774 – Elizabeth Ann Seton, American nun and saint ( d. 1821 )

* 1821 – Anita Garibaldi, Brazilian wife of Giuseppe Garibaldi ( d. 1849 )

Anne's mother, Maria Branwell ( 1783 – 1821 ), was the daughter of Thomas Branwell, a successful, property-owning grocer and tea merchant in Penzance and Anne Carne, the daughter of a silversmith.

* 1821 – Missouri is admitted as the 24th U. S. state.

* 1821 – Jay Cooke, American financier, founded Jay Cooke & Company ( d. 1905 )

* 1821 – Atkinson & Alexander publish The Saturday Evening Post for the first time as a weekly newspaper.

* 1821 – Louis Vuitton, French fashion designer, founded Louis Vuitton ( d. 1892 )

* 1821 – James Springer White, American theologian ( d. 1881 )

* 1821 – Patriarch Gregory V of Constantinople is hanged by the Ottoman government from the main gate of the Patriarchate and his body is thrown into the Bosphorus.

People starting with John Oxley in 1817, 1818 and 1821, followed by Charles Sturt in 1829 – 1830 attempted to follow the westward-flowing rivers to find an " inland sea ", but these were found to all flow into the Murray River and Darling River which turn south.

Men Playing Board Games – from The Sougandhika Parinaya Manuscript ( 1821 CE )

# Napoléon ( I ) Bonaparte ( 1769 – 1821 ) Emperor

* Christian ( French actor ) ( 1821 – 1889 ), stage name of Christian Perrin, a 19th-century French actor and singer

* The Consulate of Argos ( from 26 May 1821, under the Senate of the Peloponnese ) had a single head of state, styled consul, 28 March 1821 – 26 May 1821: Stamatellos Antonopoulos

* The Consulate of East Greece ( Livadeia ) ( from 15 November 1821, under the Areopagus of East Greece ) was headed 1 April 1821 – 15 November 1821 by three Consuls: Lambros Nakos, Ioannis Logothetis & Ioannis Filon

* Frederick William Cumberland ( 1821 – 1881 ), engineer and politician

** Edward Levett Darwin ( 1821 – 1901 ), solicitor and author

The US natural gas industry started in 1821 at Fredonia, Chautauqua County, New York, when William Hart dug a well to a depth of into gas-bearing shale, then drilled a borehole further, and piped the natural gas to a nearby inn where it was burned for illumination.

The island's first known sighting by Europeans was on 21 August 1821 by the British ship Eliza Francis ( or Eliza Frances ) owned by Edward, Thomas and William Jarvis and commanded by Captain Brown.

* 1821 – William Poole, American gangster ( d. 1855 )

* 1821 – William Henry Vanderbilt, American businessman ( d. 1885 )

* 1821 – Princess Elizabeth of Clarence, daughter of King William IV, granddaughter of King George III ( b. 1820 )

* William I, Elector of Hesse ( 1743 – 1821 )

William Gladstone was educated from 1816 to 1821 at a preparatory school at the vicarage of St Thomas's Church at Seaforth, close to his family's residence, Seaforth House.

In 1821 William followed in the footsteps of his older brothers and attended Eton College before matriculating in 1828 at Christ Church, Oxford, where he read Classics and Mathematics, although he had no great interest in mathematics.

* December 8 – William Henry Vanderbilt, American entrepreneur ( b. 1821 )

* December 11 – William Milligan, Scottish theologian ( b. 1821 )

* March 8 – William Poole, infamous member of New York City's Bowery Boys gang ( b. 1821 )

In 1821 William Conybeare and Henry De la Beche, both members of the Geological Society of London, collaborated on a paper that analysed in detail the specimens found by Anning and others.

William Conybeare named it Plesiosaurus ( near lizard ) because he thought it more like modern reptiles than the ichthyosaur had been, and he described it in the same 1821 paper he co-authored with Henry De la Beche on ichthyosaur anatomy.

This period included a panoply of international ‘ great demographers ’ like Adolphe Quételet ( 1796 – 1874 ), William Farr ( 1807 – 1883 ), Louis-Adolphe Bertillon ( 1821 – 1883 ) and his son Jacques ( 1851 – 1922 ), Joseph Körösi ( 1844 – 1906 ), Anders Nicolas Kaier ( 1838 – 1919 ), Richard Böckh ( 1824 – 1907 ), Émile Durkheim ( 1858-1917 ), Wilhelm Lexis ( 1837 – 1914 ) and Luigi Bodio ( 1840 – 1920 ) contributed to the development of demography and to the toolkit of methods and techniques of demographic analysis.

The first white settler in the area that would become Montgomery County was William Offield, earlier of Tennessee, who arrived in 1821 with his wife Jennie ( née Laughlin ) and one child and settled near the confluence of Offield Creek and Sugar Creek, about five miles ( 8 km ) southwest of Crawfordsville.

* William Irving ( New York ), ( 1766 – 1821 ), U. S. Congressman from New York

* William Thomas Mercer ( 1821 – 1879 ), British Colonial Secretary in Hong Kong, 1859 – 1868

For about 40 years William Kelly ( 1821 – 1906 ) was his chief interpreter and continued to be a staunch supporter until his own death.

During 1821 the President of the Board of Trade, William Huskisson, composed a Commons Committee report which recommended a return to the " practically free " trade of the pre-1815 years.

Its most notable member was the classicist William Kelly ( 1821 – 1906 ).

* William Smith ( congressman ), member of the U. S. House of Representatives from Virginia ( 1821 – 1827 )

* William Durkee Williamson ( 1779 – 1846 ) a governor of Maine ( 1821 ) was born in town.

In 1821, William and Jennie Offield had built a cabin on a little creek, later to be known as Offield Creek, four miles southwest of the future site of Crawfordsville.