April 20

Pre-1600

 * 1303 – The Sapienza University of Rome is instituted by a bull of Pope Boniface VIII.

1601–1900

 * 1653 – Oliver Cromwell dissolves England's Rump Parliament.
 * 1657 – English Admiral Robert Blake destroys a Spanish silver fleet, under heavy fire from the shore, at the Battle of Santa Cruz de Tenerife.
 * 1657  – Freedom of religion is granted to the Jews of New Amsterdam (later New York City).
 * 1752 – Start of Konbaung–Hanthawaddy War, a new phase in the Burmese Civil War (1740–57).
 * 1770 – The Georgian king, Erekle II, abandoned by his Russian ally Count Totleben, wins a victory over Ottoman forces at Aspindza.
 * 1775 – American Revolutionary War: The Siege of Boston begins, following the battles at Lexington and Concord.
 * 1789 – George Washington arrives at Grays Ferry, Philadelphia, while en route to Manhattan for his inauguration.
 * 1792 – France declares war against the "King of Hungary and Bohemia", the beginning of the French Revolutionary Wars.
 * 1800 – The Septinsular Republic is established.
 * 1809 – Two Austrian army corps in Bavaria are defeated by a First French Empire army led by Napoleon at the Battle of Abensberg on the second day of a four-day campaign that ended in a French victory.
 * 1828 – René Caillié becomes the second non-Muslim to enter Timbuktu, following Major Gordon Laing. He would also be the first to return alive.
 * 1836 – U.S. Congress passes an act creating the Wisconsin Territory.
 * 1861 – American Civil War: Robert E. Lee resigns his commission in the United States Army in order to command the forces of the state of Virginia.
 * 1861  – Thaddeus S. C. Lowe, attempting to display the value of balloons, makes record journey, flying 900 miles from Cincinnati to South Carolina.
 * 1862 – Louis Pasteur and Claude Bernard complete the experiment disproving the theory of spontaneous generation.
 * 1865 – Astronomer Angelo Secchi demonstrates the Secchi disk, which measures water clarity, aboard Pope Pius IX's yacht, the L'Immaculata Concezion.
 * 1876 – The April Uprising begins. Its suppression shocks European opinion, and Bulgarian independence becomes a condition for ending the Russo-Turkish War.
 * 1884 – Pope Leo XIII publishes the encyclical Humanum genus, condemning Freemasonry.
 * 1898 – U.S. President William McKinley signs a joint resolution to Congress for declaration of war against Spain, beginning the Spanish–American War.

1901–present

 * 1902 – Pierre and Marie Curie refine radium chloride.
 * 1908 – Opening day of competition in the New South Wales Rugby League.
 * 1914 – Nineteen men, women, and children participating in a strike are killed in the Ludlow Massacre during the Colorado Coalfield War.
 * 1918 – Manfred von Richthofen, a.k.a. The Red Baron, shoots down his 79th and 80th victims, his final victories before his death the following day.
 * 1922 – The Soviet government creates South Ossetian Autonomous Oblast within Georgian SSR.
 * 1945 – World War II: U.S. troops capture Leipzig, Germany, only to later cede the city to the Soviet Union.
 * 1945  – World War II: Führerbunker: On his 56th birthday Adolf Hitler makes his last trip to the surface to award Iron Crosses to boy soldiers of the Hitler Youth.
 * 1945  – Twenty Jewish children used in medical experiments at Neuengamme are killed in the basement of the Bullenhuser Damm school.
 * 1946 – The League of Nations officially dissolves, giving most of its power to the United Nations.
 * 1961 – Cold War: Failure of the Bay of Pigs Invasion of US-backed Cuban exiles against Cuba.
 * 1968 – English politician Enoch Powell makes his controversial "Rivers of Blood" speech.
 * 1968  – South African Airways Flight 228 crashes near the Hosea Kutako International Airport in South West Africa (now Namibia), killing 123 people.
 * 1972 – Apollo program: Apollo 16 Lunar Module, commanded by John Young and piloted by Charles Duke, lands on the Moon.
 * 1998 – Air France Flight 422 crashes after taking off from El Dorado International Airport in Bogotá, Colombia, killing all 53 people on board.
 * 1999 – Columbine High School massacre: Eric Harris and Dylan Klebold kill 13 people and injure 24 others before committing suicide at Columbine High School in Columbine, Colorado.
 * 2004 - The Nicoll Highway in Singapore collapsed, killing four workers.
 * 2007 – Johnson Space Center shooting: William Phillips barricades himself with a handgun in NASA's Johnson Space Center in Houston, Texas before killing a male hostage and himself.
 * 2008 – Danica Patrick wins the Indy Japan 300 becoming the first female driver in history to win an Indy car race.
 * 2010 – The Deepwater Horizon drilling rig explodes in the Gulf of Mexico, killing eleven workers and beginning an oil spill that would last six months.
 * 2012 – One hundred twenty-seven people are killed when a plane crashes in a residential area near the Benazir Bhutto International Airport near Islamabad, Pakistan.
 * 2013 – A 6.6-magnitude earthquake strikes Lushan County, Ya'an, in China's Sichuan province, killing at least 193 people and injuring thousands.
 * 2015 – Ten people are killed in a bomb attack on a convoy carrying food supplies to a United Nations compound in Garowe in the Somali region of Puntland.
 * 2020 – For the first time in history, oil prices drop below zero, an effect of the 2020 Russia-Saudi Arabia oil price war.
 * 2021 – State of Minnesota v. Derek Michael Chauvin: Derek Chauvin is found guilty of all charges in the murder of George Floyd by the Fourth Judicial District Court of Minnesota.
 * 2023 – SpaceX's Starship rocket, the largest and most powerful rocket ever built, launches for the first time. It explodes 4 minutes into flight.

Pre-1600

 * 1494 – Johannes Agricola, German theologian and reformer (d. 1566)
 * 1544 – Renata of Lorraine, Duchess consort of Bavaria (d. 1602)
 * 1586 – Rose of Lima, Peruvian mystic and saint (d. 1617)

1601–1900

 * 1633 – Emperor Go-Kōmyō of Japan (d. 1654)
 * 1646 – Charles Plumier, French botanist and author (d. 1704)
 * 1650 – William Bedloe, English spy (d. 1680)
 * 1718 – David Brainerd, American missionary (d. 1747)
 * 1723 – Cornelius Harnett, American merchant, farmer, and politician (d. 1781)
 * 1727 – Florimond Claude, Comte de Mercy-Argenteau, Belgian-Austrian minister and diplomat (d. 1794)
 * 1745 – Philippe Pinel, French physician and psychiatrist (d. 1826)
 * 1748 – Georg Michael Telemann, German composer and theologian (d. 1831)
 * 1808 – Napoleon III, French politician, 1st President of France, Emperor of French Second Empire (d. 1873)
 * 1816 – Bogoslav Šulek, Croatian philologist, historian, and lexicographer (d. 1895)
 * 1818 – Heinrich Göbel, German-American mechanic and engineer (d. 1893)
 * 1826 – Dinah Craik, English author and poet (d. 1887)
 * 1839 – Carol I of Romania, King of Romania (d. 1914)
 * 1840 – Odilon Redon, French painter and illustrator (d. 1916)
 * 1850 – Daniel Chester French, American sculptor, designed the Lincoln statue (d. 1931)
 * 1851 – Alexander Dianin, Russian chemist (d. 1918)
 * 1851  – Siegmund Lubin, Polish-American businessman, founded the Lubin Manufacturing Company (d. 1923)
 * 1860 – Justinien de Clary, French target shooter (d. 1933)
 * 1871 – Sydney Chapman, English economist and civil servant (d. 1951)
 * 1873 – James Harcourt, English character actor (d. 1951)
 * 1875 – Vladimir Vidrić, Croatian poet and lawyer (d. 1909)
 * 1879 – Paul Poiret, French fashion designer (d. 1944)
 * 1882 – Holland Smith, American general (d. 1967)
 * 1884 – Princess Beatrice of Saxe-Coburg and Gotha (d. 1966)
 * 1884  – Oliver Kirk, American boxer (d. 1960)
 * 1884  – Daniel Varoujan, Armenian poet and educator (d. 1915)
 * 1889 – Albert Jean Amateau, Turkish rabbi, lawyer, and activist (d. 1996)
 * 1889  – Prince Erik, Duke of Västmanland (d. 1918)
 * 1889  – Marie-Antoinette de Geuser, French mystic (d. 1918)
 * 1889  – Adolf Hitler, Austrian-born German politician, Führer of Nazi Germany (d. 1945)
 * 1889  – Tonny Kessler, Dutch footballer (d. 1960)
 * 1890 – Maurice Duplessis, Canadian lawyer and politician, 16th Premier of Quebec (d. 1959)
 * 1890  – Adolf Schärf, Austrian soldier and politician, 6th President of Austria (d. 1965)
 * 1891 – Dave Bancroft, American baseball player and manager (d. 1972)
 * 1893 – Harold Lloyd, American actor, comedian, and producer (d. 1971)
 * 1893  – Joan Miró, Spanish painter and sculptor (d. 1983)
 * 1895 – Henry de Montherlant, French essayist, novelist, and dramatist (d. 1972)
 * 1896 – Wop May, Canadian captain and pilot (d. 1952)
 * 1899 – Alan Arnett McLeod, Canadian lieutenant, Victoria Cross recipient (d. 1918)

1901–present

 * 1904 – Bruce Cabot, American actor (d. 1972)
 * 1907 – Miran Bakhsh, Pakistani cricketer (d. 1991)
 * 1907  – Augoustinos Kantiotes, Greek bishop (d. 2010)
 * 1908 – Lionel Hampton, American vibraphone player, pianist, bandleader, and actor (d. 2002)
 * 1910 – Fatin Rüştü Zorlu, Turkish diplomat and politician (d. 1961)
 * 1913 – Mimis Fotopoulos, Greek actor and poet (d. 1986)
 * 1913  – Willi Hennig, German biologist and entomologist (d. 1976)
 * 1914 – Betty Lou Gerson, American actress (d. 1999)
 * 1915 – Joseph Wolpe, South African psychotherapist and physician (d. 1997)
 * 1916 – Nasiba Zeynalova, Azerbaijani actress (d. 2004)
 * 1918 – Kai Siegbahn, Swedish physicist and academic, Nobel Prize laureate (d. 2007)
 * 1919 – Richard Hillary, Australian lieutenant and pilot (d. 1943)
 * 1920 – Frances Ames, South African neurologist, psychiatrist, and human rights activist (d. 2002)
 * 1920  – Clement Isong, Nigerian banker and politician, Governor of Cross River State (d. 2000)
 * 1920  – John Paul Stevens, American lawyer and jurist, Associate Justice of the Supreme Court of the United States (d. 2019)
 * 1921 – Katarína Kolníková, Slovak actress (d. 2006)
 * 1923 – Mother Angelica, American nun and broadcaster, founded Eternal Word Television Network (d. 2016)
 * 1923  – Irene Lieblich, Polish-American painter and illustrator (d. 2008)
 * 1923  – Tito Puente, American drummer and producer (d. 2000)
 * 1924 – Nina Foch, Dutch-American actress (d. 2008)
 * 1924  – Leslie Phillips, English actor and producer (d. 2022)
 * 1924  – Guy Rocher, Canadian sociologist and academic
 * 1925 – Ernie Stautner, German-American football player and coach (d. 2006)
 * 1925  – Elena Verdugo, American actress (d. 2017)
 * 1927 – Bud Cullen, Canadian judge and politician, 1st Canadian Minister of Employment and Immigration (d. 2005)
 * 1927  – Phil Hill, American race car driver (d. 2008)
 * 1927  – K. Alex Müller, Swiss physicist and academic, Nobel Prize laureate (d. 2023)
 * 1928 – Robert Byrne, American chess player and author (d. 2013)
 * 1928  – Johnny Gavin, Irish international footballer (d. 2007)
 * 1930 – Dwight Gustafson, American composer and conductor (d. 2014)
 * 1930  – Antony Jay, English director and screenwriter (d. 2016)
 * 1931 – Michael Allenby, 3rd Viscount Allenby, English lieutenant and politician (d. 2014)
 * 1931  – John Eccles, 2nd Viscount Eccles, English businessman and politician
 * 1932 – Myriam Bru, French actress
 * 1936 – Lisa Davis, English-American actress
 * 1936  – Pauli Ellefsen, Faroese technician, surveyor, and politician, 6th Prime Minister of the Faroe Islands (d. 2012)
 * 1936  – Pat Roberts, American captain, journalist, and politician
 * 1937 – Jiří Dienstbier, Czech journalist and politician, Czech Minister of Foreign Affairs (d. 2011)
 * 1937  – Harvey Quaytman, American painter and educator (d. 2002)
 * 1937  – George Takei, American actor
 * 1938 – Betty Cuthbert, Australian sprinter (d. 2017)
 * 1938  – Manfred Kinder, German runner
 * 1938  – Eszter Tamási, Hungarian actress (d. 1991)
 * 1939 – Peter S. Beagle, American author and screenwriter
 * 1939  – Gro Harlem Brundtland, Norwegian physician and politician, 22nd Prime Minister of Norway
 * 1939  – Johnny Tillotson, American singer-songwriter
 * 1940 – James Gammon, American actor (d. 2010)
 * 1941 – Ryan O'Neal, American actor (d. 2023)
 * 1943 – Alan Beith, English academic and politician
 * 1943  – John Eliot Gardiner, English conductor and director
 * 1944 – Toivo Aare, Estonian journalist and author (d. 1999)
 * 1945 – Michael Brandon, American actor and director
 * 1945  – Olga Karlatos, Greek actress and Bermudian lawyer
 * 1945  – Thein Sein, Burmese general and politician, 8th President of Burma
 * 1945  – Naftali Temu, Kenyan runner (d. 2003)
 * 1945  – Steve Spurrier, American football player and coach
 * 1946 – Sandro Chia, Italian painter and sculptor
 * 1947 – Rita Dionne-Marsolais, Canadian economist and politician
 * 1947  – Viktor Suvorov, Russian intelligence officer, historian, and author
 * 1948 – Matthias Kuhle, German geographer and academic (d. 2015)
 * 1949 – Veronica Cartwright, English-American actress
 * 1949  – Toller Cranston, Canadian-Mexican figure skater and painter (d. 2015)
 * 1949  – Massimo D'Alema, Italian journalist and politician, 76th Prime Minister of Italy
 * 1949  – Jessica Lange, American actress
 * 1950 – Alexander Lebed, Russian general and politician (d. 2002)
 * 1950  – N. Chandrababu Naidu, Indian politician, 13th Chief Minister of Andhra Pradesh
 * 1951 – Luther Vandross, American singer-songwriter and producer (d. 2005)
 * 1952 – Louka Katseli, Greek economist and politician
 * 1953 – Sebastian Faulks, English journalist and author
 * 1953  – James Chance, American musician (d. 2024)
 * 1955 – Donald Pettit, American engineer and astronaut
 * 1955  – Svante Pääbo, Swedish geneticist and Nobel Laureate
 * 1956 – Beatrice Ask, Swedish politician, Swedish Minister for Justice
 * 1956  – Peter Chelsom, English film director, writer, and actor
 * 1956  – Kakha Bendukidze, Georgian economist and politician (d. 2014)
 * 1958 – Viacheslav Fetisov, Russian ice hockey player and coach
 * 1960 – Debbie Flintoff-King, Australian hurdler and coach
 * 1961 – Don Mattingly, American baseball player, coach, and manager
 * 1961  – Konstantin Lavronenko, Russian actor
 * 1963 – Rachel Whiteread, English sculptor
 * 1964 – John Carney, American football player
 * 1964  – Crispin Glover, American actor and filmmaker
 * 1964  – Andy Serkis, English actor and director
 * 1964  – Rosalynn Sumners, American figure skater
 * 1965 – Kostis Chatzidakis, Greek politician, Ministry of Economy, Infrastructure, Shipping and Tourism
 * 1965  – Léa Fazer, Swiss film director, screenwriter and actress
 * 1966 – David Chalmers, Australian philosopher and academic
 * 1966  – David Filo, American businessman, co-founded Yahoo!
 * 1967 – Mike Portnoy, American drummer and songwriter
 * 1968 – Julia Morris, Australian entertainer
 * 1969 – Felix Baumgartner, Austrian daredevil
 * 1969  – Will Hodgman, Australian politician, 45th Premier of Tasmania
 * 1970 – Shemar Moore, American actor
 * 1971 – Allan Houston, American basketball player
 * 1972 – Carmen Electra, American model and actress
 * 1972  – Stephen Marley, Jamaican-American musician
 * 1973 – Julie Powell, American food writer and memoirist (d. 2022)
 * 1975 – Killer Mike, American rapper
 * 1978 – Carl Greenidge, English cricketer
 * 1980 – Emma Husar, Australian politician
 * 1983 – Miranda Kerr, Australian model
 * 1987 – Jorge Pinto, Portuguese politician
 * 1988 – Brandon Belt, American baseball player
 * 1989 – Vannesa Rosales, Venezuelan activist and teacher
 * 1990 – Jason Behrendorff, Australian cricketer
 * 1991 – Luke Kuechly, American football player
 * 1997 – Alexander Zverev, German tennis player

Pre-1600

 * 689 – Cædwalla, king of Wessex (b. 659)
 * 888 – Xi Zong, Chinese emperor (b. 862)
 * 1099 – Peter Bartholomew (b. 1061)
 * 1164 – Antipope Victor IV
 * 1176 – Richard de Clare, 2nd Earl of Pembroke, English-Irish politician, Lord Chief Justice of Ireland (b. 1130)
 * 1248 – Güyük Khan, Mongol ruler, 3rd Great Khan of the Mongol Empire (b. 1206)
 * 1284 – Hōjō Tokimune, regent of Japan (b. 1251)
 * 1314 – Pope Clement V (b. 1264)
 * 1322 – Simon Rinalducci, Italian Augustinian friar
 * 1502 – Mary of Looz-Heinsberg, Dutch noble (b. 1424)
 * 1521 – Zhengde, Chinese emperor (b. 1491)
 * 1534 – Elizabeth Barton, English nun and martyr (b. 1506)
 * 1558 – Johannes Bugenhagen, German priest and theologian (b. 1485)

1601–1900

 * 1643 – Christoph Demantius, German composer and poet (b. 1567)
 * 1703 – Lancelot Addison, English clergyman and educator (b. 1632)
 * 1769 – Chief Pontiac, American tribal leader (b. 1720)
 * 1831 – John Abernethy, English surgeon and anatomist (b. 1764)
 * 1873 – William Tite, English architect, designed the Royal Exchange (b. 1798)
 * 1874 – Alexander H. Bailey, American lawyer, judge, and politician (b. 1817)
 * 1881 – William Burges, English architect and designer (b. 1827)
 * 1886 – Charles-François-Frédéric, marquis de Montholon-Sémonville, French general and diplomat, French ambassador to the United States (b. 1814)
 * 1887 – Muhammad Sharif Pasha, Greek-Egyptian politician, 2nd Prime Minister of Egypt (b. 1826)
 * 1899 – Joseph Wolf, German ornithologist and illustrator (b. 1820)

1901–present

 * 1902 – Joaquim de Sousa Andrade, Brazilian poet and educator (b. 1833)
 * 1912 – Bram Stoker, Anglo-Irish novelist and critic, created Count Dracula (b. 1847)
 * 1918 – Jussi Merinen, Finnish politician (b. 1873)
 * 1918 – Karl Ferdinand Braun, German-American physicist and academic, Nobel Prize laureate (b. 1850)
 * 1927 – Enrique Simonet, Spanish painter and educator (b. 1866)
 * 1929 – Prince Henry of Prussia (b. 1862)
 * 1931 – Sir Cosmo Duff-Gordon, 5th Baronet, Scottish-English fencer and businessman (b. 1862)
 * 1932 – Giuseppe Peano, Italian mathematician and philosopher (b. 1858)
 * 1935 – John Cameron, Scottish footballer and manager (b. 1872)
 * 1935  – Lucy, Lady Duff-Gordon, English fashion designer (b. 1863)
 * 1942 – Jüri Jaakson, Estonian businessman and politician, 6th State Elder of Estonia (b. 1870)
 * 1944 – Elmer Gedeon, American baseball player and pilot (b. 1917)
 * 1945 – Erwin Bumke, Polish-German jurist and politician (b. 1874)
 * 1946 – Mae Busch, Australian actress (b. 1891)
 * 1947 – Christian X of Denmark (b. 1870)
 * 1951 – Ivanoe Bonomi, Italian politician, 25th Prime Minister of Italy (b. 1873)
 * 1967 – Léo-Paul Desrosiers, Canadian journalist and author (b. 1896)
 * 1968 – Rudolph Dirks, German-American illustrator (b. 1877)
 * 1969 – Vjekoslav Luburić, Croatian Ustaše official and concentration camp administrator (b. 1914)
 * 1980 – M. Canagaratnam, Sri Lankan politician (b. 1924)
 * 1982 – Archibald MacLeish, American poet, playwright, and lawyer (b. 1892)
 * 1986 – Sibte Hassan, Pakistani journalist, scholar, and activist (b. 1916)
 * 1991 – Steve Marriott, English singer-songwriter and producer (b. 1947)
 * 1991  – Don Siegel, American director and producer (b. 1912)
 * 1992 – Marjorie Gestring, American springboard diver (b. 1922)
 * 1992  – Benny Hill, English comedian, actor, and screenwriter (b. 1924)
 * 1993 – Cantinflas, Mexican actor, producer, and screenwriter (b. 1911)
 * 1995 – Milovan Đilas, Yugoslav communist, politician, theorist and author (b. 1911)
 * 1996 – Trần Văn Trà, Vietnamese general and politician (b. 1918)
 * 1999 – Rick Rude, American professional wrestler (b. 1958)
 * 1999 – Rachel Scott, American victim of Columbine High School massacre (b. 1981)
 * 1999 – Cassie Bernall, American victim of Columbine High School massacre (b. 1981)
 * 2001 – Giuseppe Sinopoli, Italian conductor and composer (b. 1946)
 * 2002 – Alan Dale, American singer (b. 1925)
 * 2003 – Bernard Katz, German-English biophysicist and academic, Nobel Prize laureate (b. 1911)
 * 2004 – Lizzy Mercier Descloux, French musician, singer-songwriter, composer, actress, writer and painter (b. 1956)
 * 2005 – Fumio Niwa, Japanese journalist and author (b. 1904)
 * 2007 – Andrew Hill, American pianist, composer, and bandleader (b. 1931)
 * 2007  – Michael Fu Tieshan, Chinese bishop (b. 1931)
 * 2008 – Monica Lovinescu, Romanian journalist and author (b. 1923)
 * 2010 – Dorothy Height, American educator and activist (b. 1912)
 * 2011 – Tim Hetherington, English photographer and journalist (b. 1970)
 * 2012 – Bert Weedon, English guitarist and songwriter (b. 1920)
 * 2014 – Neville Wran, Australian politician, 35th Premier of New South Wales (b. 1926)
 * 2016 – Victoria Wood, British comedian, actress and writer (b. 1953)
 * 2018 – Avicii, Swedish DJ and musician (b. 1989)
 * 2021 – Idriss Déby, Chadian politician and military officer (b. 1952)
 * 2021  – Monte Hellman, American film director (b. 1929)
 * 2021  – Les McKeown, Scottish pop singer (b. 1955)
 * 2022 – Gavin Millar, Scottish film director (b. 1938)
 * 2024 – Antonio Cantafora, Italian film and television actor (b. 1944)
 * 2024 – Andrew Davis, English conductor (b. 1944)
 * 2024 – Roman Gabriel, Filipino-American NBA American footballer
 * 2024 – Lourdes Portillo, Mexican film director, producer, and writer (b. 1943)

Holidays and observances

 * Christian feast day:
 * Agnes of Montepulciano
 * Beuno
 * Johannes Bugenhagen (Lutheran)
 * Theotimos
 * April 20 (Eastern Orthodox liturgics)
 * 420 (cannabis culture)
 * UN Chinese Language Day (United Nations)