September 20 is the 263rd day of the year (264th in leap years) in the Gregorian calendar. There are 102 days remaining until the end of the year.
Up to 1900
- 331 BC – Alexander the Great crosses the Tigris on his way to conquering the Persians.
- 1058 – Agnes de Poitou and Andrew I of Hungary meet to talk about the border zone in present-day Burgenland.
- 1187 – Saladin begins the Siege of Jerusalem.
- 1260 – The Great Prussian Uprising among the old Prussians begins against the Teutonic Knights.
- 1459 – First documented mention of Bucharest.
- 1498 – An earthquake and tsunami washes away the building housing the Great Buddha at Kotoku-in in Kamagura, Kanagawa, Japan. Since then, the Buddha statue has sat in open-air.
- 1519 – Ferdinand Magellan sets sail from Spain with 270 crew members, of whom only 18 return home in 1522. Magellan is killed in the Philippines in 1521.
- 1596 – Diego de Montemayor founds the city of Monterrey, Mexico.
- 1697 – The Treaty of Rijswijk is signed by France, England, Spain and the Holy Roman Empire, ending the Nine Years' War.
- 1848 – The American Association for the Advancement of Science is created.
- 1854 – Crimean War: British and French troops defeat the Russians in the Battle of Alma.
- 1859 – For the electric oven, American George B. Simpson is given a US patent.
- 1860 – Future King Edward VII of the United Kingdom (then the Prince of Wales), visits the United States.
- 1863 – American Civil War: The Battle of Chickamauga ends in Confederate victory.
- 1870 – The Unification of Italy is completed.
- 1881 – Chester A. Arthur is inaugurated as the 21st President of the United States. This is after the death of James Garfield the previous day, as a result of injuries from being shot on July 2 by Charles J. Guiteau.
- 1893 – The first gasoline-powered car in America debuts in Springfield, Massachusetts.
1901 – 2000
- 1906 – The Cunard Line's ship RMS Mauretania is launched in Newcastle upon Tyne.
- 1908 – Near Prince of Wales Island, Southeast Alaska, the barque (a type of ship) Star of Bengal collides with a rock and sinks, killing 110 people.
- 1909 – The British Parliament passes the South Africa Act of 1909, creating the Union of South Africa from the British colonies of Good Hope, Natal, Orange River and Transvaal.
- 1910 – The Ocean Liner SS France is launched.
- 1911 – The White Star line's RMS Olympic collides with British warship HMS Hawke.
- 1914 – World War I: The cathedral in Reims, France, is severely damaged by German artillery.
- 1920 – Foundation of the Spanish Legion.
- 1932 – Mahatma Gandhi begins a hunger strike in prison in Pune, India.
- 1942 – Holocaust: In Letychev, Ukraine, the SS murders 3,000 Jews in two days.
- 1946 – The first Cannes Film Festival is held. It still takes place every year, in May.
- 1961 – Konstantinos Dovas becomes Prime Minister of Greece.
- 1962 – African American James Meredith is temporarily barred from entering the University of Mississippi.
- 1967 – The ship RMS Queen Elizabeth 2 is launched at Clydebank near Glasgow.
- 1971 – Hurricane Irene crosses the Caribbean Sea, through Nicaragua, to the Pacific Ocean to become Hurricane Olivia; This is the first time a hurricane is known to have crossed from the Caribbean to the Pacific.
- 1973 – Billie Jean King defeats Bobby Riggs in a 'Battle of the Sexes' tennis match in Houston, Texas.
- 1977 – The Socialist Republic of Vietnam joins the UN.
- 1978 – Johannes Rau, future President of Germany, is chosen as Minister-President of North Rhine-Westphalia, a position he will hold for 20 years.
- 1979 – In the present-day Central African Republic, Jean Bedel Bokassa, self-declared Emperor Bokassa I, is overthrown.
- 1982 – NFL players begin a 57-day strike.
- 1984 – A bomb attack targets the US Embassy in Beirut, Lebanon.
- 1990 – South Ossetia declares its independence from the Republic of Georgia.
Up to 1900
- 524 – Kan B'alam I, ruler of the Mayan city of Palenque (d. 583)
- 1486 – Arthur Tudor, son of Henry VII of England (d. 1502)
- 1503 – Andrzej Frycz Modrzewski, Polish scholar, humanist and theologian (d. 1572)
- 1593 – Gottfried Scheidt, German composer and organist (d. 1661)
- 1599 – Christian the Younger of Brunswick, German Protestant military leader (d. 1626)
- 1685 – Giuseppe Matteo Alberti, Italian baroque composer and violinist (d. 1751)
- 1710 – Thomas Simpson, English mathematician (d. 1761)
- 1735 – James Keir, Scottish chemist, geologist and inventor (d. 1820)
- 1746 – Maurice Benyovszky, Hungarian explorer and writer (d. 1786)
- 1758 – Jean-Jacques Dessalines, Emperor of Haiti (d. 1806)
- 1778 – Fabian Gottlieb von Bellingshausen, Russian naval officer and explorer (d. 1852)
- 1800 – Benjamin Franklin White, American singer and composer (d. 1879)
- 1815 – Richard Dry, Australian politician, 7th Premier of Tasmania (d. 1869)
- 1820 – John F. Reynolds, American general (d. 1863)
- 1830 – Yoshida Shoin, Japanese intellectual, teacher and revolutionary (d. 1859)
- 1831 – Kate Harrington, American teacher, writer and poet (d. 1917)
- 1832 – Johann Joseph Abert, German-Bohemian composer and conductor (d. 1915)
- 1833 – Ernesto Teodoro Moneta, Italian pacifist (d. 1918)
- 1842 – James Dewar, Scottish chemist and physicist (d. 1923)
- 1843 – Nicholas Alexandrovich, Tsarevich of Russia (d. 1865)
- 1851 – Henry Arthur Jones, English writer (d. 1929)
- 1853 – Rama V, King of Siam (d. 1910)
- 1860 – James Gillett, 22nd Governor of California (d. 1937)
- 1861 – Herbert Putnam, American Librarian of Congress (d. 1955)
- 1872 – Maurice Gamelin, French army general (d. 1958)
- 1873 – Sidney Olcott, Canadian movie director (d. 1949)
- 1873 – Ferenc Szisz, Hungarian racing driver (d. 1944)
- 1875 – Matthias Erzberger, German publicist and politician (d. 1921)
- 1878 – Upton Sinclair, American writer (d. 1968)
- 1884 – Maxwell Perkins, American editor and publisher (d. 1947)
- 1885 – Jelly Roll Morton, American jazz pianist (d. 1941)
- 1885 – Enrico Mizzi, 6th Prime Minister of Malta (d. 1950)
- 1889 – Charles Reidpath, American city planner and athlete (d. 1975)
- 1890 – Linda Eenpalu, Estonian politician and activist (d. 1962)
- 1893 – Hans Scharoun, German architect (d. 1972)
- 1897 – Humberto de Alencar Castelo Branco, President of Brazil (d. 1967)
- 1899 – Leo Strauss, German-born philosopher (d. 1973)
- 1900 – Nikolay Timofeev-Ressowski, Russian geneticist (d. 1981)
1901 – 1950
- 1908 – Ernest Manning, Canadian preacher and politician, Premier of Alberta (d. 1996)
- 1911 – Pandit Shri Ram Sharma Acharya, Indian philosopher (d. 1991)
- 1914 – Kenneth More, English actor (d. 1982)
- 1916 – Malik Meraj Khalid, Pakistani politician (d. 2003)
- 1917 – Red Auerbach, American basketball coach (d. 2006)
- 1917 – Fernando Rey, Spanish actor (d. 1994)
- 1917 – Obdulio Varela, Uruguayan footballer (d. 1996)
- 1920 – Alberto de Lacerda, Portuguese poet (d. 2007)
- 1920 – Jay Ward, American animator, producer and screenwriter (d. 1989)
- 1921 – Chico Hamilton, American jazz drummer and bandleader (d. 2013)
- 1921 – Carlo Parola, Italian footballer (d. 2000)
- 1923 – Akkineni Nageswara Rao, Indian actor and producer (d. 2014)
- 1924 – Gogi Grant, American singer (d. 2016)
- 1925 – Ananda Mahidol, King of Thailand (d. 1946)
- 1925 – James Bernard, English movie composer (d. 2001)
- 1925 – Bobby Nunn, American singer (d. 1986)
- 1926 – Libero Liberati, Italian motorcycle racer (d. 1962)
- 1927 – John Dankworth, English jazz musician (d. 2010)
- 1927 – Rachel Roberts, Welsh actress (d. 1980)
- 1928 – William J. Edwards, American politician (d. 2019)
- 1928 – Donald Hall, American poet (d. 2018)
- 1929 – Anne Meara, American comic and actress (d. 2015)
- 1929 – Hans von Borsody, Austrian-German actor (d. 2013)
- 1929 – Joe Temperley, Scottish jazz saxophonist (d. 2016)
- 1934 – Sophia Loren, Italian actress
- 1935 – Walter Eschweiler, German football referee
- 1936 – Andrew Davies, Welsh writer
- 1937 – Birgitta Dahl, Swedish politician
- 1937 – Monica Zetterlund, Swedish actress and singer (d. 2005)
- 1940 – Taro Aso, former Prime Minister of Japan
- 1942 – Gerald Tremblay, 41st Mayor of Montreal
- 1942 – Rose Francine Rogombé, Interim President of Gabon (d. 2015)
- 1943 – Sani Abacha, President of Nigeria (d. 1998)
- 1946 – Dorothy Hukill, American politician (d. 2018)
- 1947 – Wojciech Kurtyka, Polish mountaineer
- 1947 – Mia Martini, Italian singer and actress (d. 1995)
- 1948 – George R. R. Martin, American writer, screenwriter and producer
- 1948 – Chuck Panozzo, American musician
- 1948 – John Panozzo, American musician (d. 1996)
- 1949 – Anthony Denison, American actor
- 1949 – Mahesh Bhatt, Indian director, producer and screenwriter
- 1949 – Victoria Mallory, American singer and actress (d. 2014)
1951 – 1975
- 1952 – Manuel Zelaya, former President of Honduras
- 1954 – Anne McIntosh, Scottish politician
- 1956 – Gary Cole, American actor
- 1956 – Steve Coleman, American jazz saxophonist, bandleader and composer
- 1959 – Joseph Alessi, American trombonist
- 1960 – Dave Hemingway, English singer-songwriter
- 1961 – Caroline Flint, English politician
- 1962 – Jim Al-Khalili, English physicist, writer and broadcaster
- 1966 – Nuno Bettencourt, Portuguese guitarist, singer-songwriter and record producer
- 1966 – Douglas Gordon, Scottish artist
- 1967 – Kristen Johnston, American actress
- 1967 – Gunnar Nelson, American singer-songwriter and guitarist
- 1967 – Matthew Nelson, American singer-songwriter and bass player
- 1969 – Richard Witschge, Dutch footballer
- 1971 – Tinna Björk Baldvinsdóttir, Icelandic footballer and psychologist
- 1971 – Henrik Larsson, Swedish footballer
- 1972 – Victor Ponta, former Prime Minister of Romania
- 1973 – Jo Pavey, English runner
- 1975 – Juan Pablo Montoya, Colombian race car driver
- 1975 – Asia Argento, Italian actress
From 1976
- 1976 – Jon Bernthal, American actor
- 1977 – Namie Amuro, Japanese pop singer
- 1979 – Dan Gillespie Sells, British musician (The Feeling)
- 1980 – Judith Schalansky, German writer, book designer and publisher
- 1980 – Robert Koren, Slovenian footballer
- 1980 – Igor Vori, Croatian handball player
- 1981 – Feliciano López, Spanish tennis player
- 1981 – Ryan Tandy, Australian rugby league player (d. 2014)
- 1982 – Aaron Burkart, German rally driver
- 1982 – Brian Fortuna, American dancer and choreographer
- 1983 – Freya Murray, Scottish athlete
- 1984 – Brian Joubert, French figure skater
- 1987 – Gain, South Korean singer, actress and entertainer
- 1987 – Deon McCaulay, Belizean footballer
- 1987 – Reza Ghoochannejhad, Iranian footballer
- 1988 – Sergei Bobrovsky, Russian ice hockey player
- 1990 – John Tavares, Canadian ice hockey player
- 1990 – Phillip Phillips, American Idol winner
- 1990 – Waylon Francis, Costa Rican footballer
- 1991 – Spencer Locke, American actress
- 1992 – Safura Alizadeh, Azerbaijani singer
- 1992 – Peter Prevc, Slovenian ski jumper
- 1993 – Julian Draxler, German footballer
- 1995 – Laura Dekker, Dutch-New Zealand sailor
- 1995 – Sammi Hanratty, American actress
- 1996 – Marlos Moreno, Colombian footballer
Up to 1950
- 911 – Louis the Child, King of the East Franks (b. 893)
- 1328 – Ibn Taymiyyah, Syrian theologian and scholar (b. 1263)
- 1384 – King Louis of Naples (b. 1339)
- 1460 – Gilles Binchois, Flemish composer (b. 1400)
- 1590 – Lodovico Agostini, Italian composer (b. 1534)
- 1629 – Jan Pieterszoon Coen, Dutch colonial governor (b. 1587)
- 1630 – Claudio Saracini, Italian composer (b. 1586)
- 1684 – Kim Seok-ju, Korean scholar, politician and author (b. 1634)
- 1793 – Fletcher Christian, English mutineer (b. 1764)
- 1839 – Thomas Hardy, 1st Baronet, British admiral (b. 1769)
- 1840 – Jose Gaspar Rodriguez de Francia, Paraguayan politician (b. 1766)
- 1845 – Matvei Gedenschtorm, Russian explorer (b. 1780)
- 1852 – Philander Chase, American bishop and educator (b. 1775)
- 1863 – Jacob Grimm, German writer and folklorist (b. 1785)
- 1898 – Theodor Fontane, German writer (b. 1819)
- 1908 – Pablo de Sarasate, Spanish violinist and composer (b. 1844)
- 1919 – Ramón Barros Luco, President of Chile (b. 1835)
- 1927 – George Nichols, American actor (b. 1864)
- 1930 – Gombojab Tsybikov, Russian anthropologist and explorer (b. 1873)
- 1932 – John Ellis, English executioner (b. 1874)
- 1933 – Annie Besant, British writer, philosopher and journalist (b. 1847)
- 1945 – Augusto Tasso Fragoso, President of Brazil (b. 1869)
- 1945 – William Seabrook, American occultist, journalist and explorer (b. 1884)
- 1946 – Raimu, French actor (b. 1883)
- 1947 – Fiorello La Guardia, Mayor of New York City (b. 1882)
- 1948 – Husain Salaahudin, Maldivian scholar, poet and writer (b. 1881)
1951 – 2010
- 1957 – Jean Sibelius, Finnish composer (b. 1865)
- 1970 – Alexandros Othonaios, Greek general and Prime Minister (b. 1879)
- 1971 – Giorgos Seferis, Greek poet (b. 1900)
- 1973 – Jim Croce, American singer-songwriter (b. 1943)
- 1975 – Saint-John Perse, French diplomat and writer (b. 1887)
- 1979 – Ludvik Svoboda, Czechoslovakian politician (b. 1895)
- 1993 – Erich Hartmann, German pilot and fighter ace (b. 1922)
- 1994 – Abioseh Nicol, Sierra Leonean diplomat and author (b. 1921)
- 1996 – Paul Erdős, Hungarian mathematician (b. 1913)
- 1996 – Reuben Kamenga, 1st Vice president of Zambia (b. 1929)
- 1998 – Muriel Humphrey Brown, United States Senator and wife of Hubert Humphrey (b. 1912)
- 1999 – Raisa Gorbachova, wife of Mikhail Gorbachev (b. 1932)
- 2002 – Sergei Bodrov, Jr., Russian actor (b. 1971)
- 2003 – Gordon Mitchell, American actor (b. 1923)
- 2003 – Simon Muzenda, Zimbabwean politician (b. 1922)
- 2004 – Brian Clough, English football manager (b. 1935)
- 2005 – Simon Wiesenthal, Austrian Holocaust survivor (b. 1908)
- 2006 – Sven Nykvist, Swedish cameraman and director (b. 1922)
- 2010 – Fud Leclerc, Belgian singer (b. 1924)
From 2011
- 2011 – Burhanuddin Rabbani, President of Afghanistan (b. 1940)
- 2012 – Fortunato Baldelli, Italian cardinal (b. 1935)
- 2014 – Anatoly Berezovoy, Soviet-Russian cosmonaut (b. 1942)
- 2014 – Polly Bergen, American actress (b. 1930)
- 2014 – Rob Bironas, American football player (b. 1978)
- 2014 – Vince Callahan, American politician (b. 1931)
- 2014 – Pino Cerami, Italian-Belgian cyclist (b. 1922)
- 2014 – Takako Doi, Japanese politician (b. 1928)
- 2014 – George Sluizer, Dutch film director (b. 1932)
- 2015 – Jack Larson, American actor, screenwriter and producer (b. 1928)
- 2015 – C. K. Williams, American poet (b. 1936)
- 2015 – Siegfried Gottwald, German mathematician (b. 1943)
- 2016 – Richie Dunn, American ice hockey player (b. 1957)
- 2016 – Peter Leo Gerety, American bishop (b. 1912)
- 2016 – Curtis Hanson, American movie director and screenwriter (b. 1945)
- 2017 – Ene Mihkelson, Estonian novelist (b. 1944)
- 2017 – Lillian Ross, American journalist and author (b. 1918)
- 2017 – Teddy Taylor, British politician (b. 1937)
- 2017 – Arne Solli, Norwegian military officer (b. 1938)
- 2018 – Fadhil Jalil al-Barwari, Iraqi military officer (b. 1966)
- 2018 – John Cunliffe, English children's writer (b. 1933)
- 2018 – Inge Feltrinelli, German-Italian publisher and photographer (b. 1930)
- 2018 – George N. Hatsopoulos, Greek-born American chemical engineer (b. 1927)
- 2018 – Laurie Mitchell, American actress (b. 1928)
- 2018 – K-Run's Park Me In First, American-bred show dog (b. 2005)
- 2018 – Mohamed Sahnoun, Algerian politician and diplomat (b. 1931)
- 2018 – Reinhard Tritscher, German skier (b. 1946)
- 2018 – Henry Wessel Jr., American photographer (b. 1942)
- 2019 – Robert Boyd, American journalist (b. 1928)
- 2019 – Howard Cassady, American football player (b. 1934)
- 2019 – Séamus Hegarty, Irish Roman Catholic prelate (b. 1940)
- 2019 – Jan Merlin, American actor (b. 1925)
- 2019 – Gregorio Martínez Sacristán, Spanish Roman Catholic prelate (b. 1946)
- 2019 – Yonrico Scott, American drummer (b. 1955)
- 2019 – Su Beng, Taiwanese dissident (b. 1918)