|April 21 in recent years
April 21 is the 111th day of the year (112th in leap years) in the Gregorian calendar. There are 254 days remaining until the end of the year.
- 753 BC - Romulus and Remus found Rome (traditional).
- 43 BC - Battle of Mutina: Mark Antony is again defeated in battle by Aulus Hirtius, who is killed. Although Antony fails to capture Mutina, Decimus Brutus is murdered shortly afterwards.
- 1509 - Henry VIII ascends the throne of England (unofficially) at the death of his father, Henry VII
- 1792 - Tiradentes, a revolutionary who was leading a movement for Brazil's independence, is hanged and quartered.
- 1836 - Texas Revolution: Battle of San Jacinto – Republic of Texas forces under Sam Houston defeat troops under Mexican General Antonio López de Santa Anna.
- 1863 - Bahá'u'lláh declares his mission as "He whom God shall make manifest". Considered the founder of the Bahá'í Faith.
- 1894 - Norway formally adopts the Krag-Jørgensen rifle as the main arm of its armed forces, a weapon that would remain in service for almost 50 years.
- 1898 - Spanish-American War: The U.S. Congress, on April 25, recognizes that a state of war exists between the United States and Spain as of this date.
- 1918 - World War I: German fighter ace Manfred von Richthofen, known as "The Red Baron", is shot down and killed over Vaux sur Somme in France.
- 1930 - A fire at a penitentiary in Columbus, kills 320 people.
- 1944 - Women in France receive the right to vote.
- 1945 - World War II: Soviet Union forces south of Berlin at Zossen attack the German High Command headquarters.
- 1952 - Secretary's Day (now Administrative Professionals' Day) is first celebrated.
- 1960 - Brasília, Brazil's capital, is officially inaugurated. At 9:30 am the Three Powers of the Republic are simultaneously transferred from the old capital, Rio de Janeiro.
- 1960 - Founding of the Orthodox Bahá'í Faith in Washington.
- 1962 - The Seattle World's Fair (Century 21 Exposition) opens. It is the first World's Fair in the U.S. since World War II. 
- 1963 - The Universal House of Justice of the Bahá'í faith is elected for the first time.
- 1965 - The 1964-1965 New York World's Fair opens for its second and final season.
- 1966 - Rastafari movement: Haile Selassie of Ethiopia visits Jamaica, an event now celebrated as Grounation Day.
- 1967 - A few days before the general election in Greece, Colonel George Papadopoulos leads a coup d'état, establishing a military regime that lasts for seven years.
- 1970 - The Hutt River Province Principality secedes from Australia
- 1975 - Vietnam War: President of South Vietnam Nguyen Van Thieu flees Saigon, as Xuan Loc, the last South Vietnamese outpost blocking a direct North Vietnamese assault on Saigon, falls.
- 1982 - Rollie Fingers of the Milwaukee Brewers becomes the first pitcher to record 300 saves.
- 1987 - The Tamil Tigers are blamed for a car bomb that explodes in the Sri Lankan capital of Colombo, killing 106 people.
- 1989 - Tiananmen Square Protests of 1989: In Beijing, around 100,000 students gather in Tiananmen Square to commemorate Chinese reform leader Hu Yaobang.
- 1994 - The first discoveries of extrasolar planets are announced by astronomer Alexander Wolszczan.
- 1555 - Ludovico Carracci, Italian painter (d. 1619)
- 1651 - Blessed Joseph Vaz, Apostle of Ceylon (d. 1711)
- 1652 - Michel Rolle, French mathematician (d. 1719)
- 1671 - John Law, Scottish economist (d. 1729)
- 1713 - Louis, Marshal of France (d. 1793)
- 1729 - Empress Catherine II of Russia (d. 1796)
- 1767 - Elisabeth of Württemberg, Empress consort of the Holy Roman Empire (d. 1790)
- 1774 - Jean-Baptiste Biot, French physicist (d. 1862)
- 1775 - Alexander Anderson, American illustrator (d. 1870)
- 1810 - John Putnam Chapin, American politician (d. 1864)
- 1811 - Alson Sherman, American politician (d. 1903)
- 1814 - Angela Georgina Burdett-Coutts, English philanthropist (d. 1906)
- 1816 - Charlotte Brontë, English author (d. 1855)
- 1837 - Fredrik Bajer, Danish politician, Nobel laureate (d. 1922)
- 1838 - John Muir, American environmentalist (d. 1914)
- 1851 - Charles Barrois, French geologist (d. 1939)
- 1864 - Max Weber, German economist and sociologist (d. 1920)
- 1870 - Edwin S. Porter, American film pioneer (d. 1941)
- 1879 - Kartini, Indonesian national figure (d. 1904)
- 1882 - Percy Williams Bridgman, American physicist, Nobel laureate (d. 1961)
- 1887 - Joe McCarthy, American baseball manager (d. 1978)
- 1889 - Paul Karrer, Swiss chemist, Nobel laureate (d. 1971)
- 1896 - Henry de Montherlant, French novelist and essayist (d. 1972)
- 1905 - Pat Brown, American politician (d. 1996)
- 1911 - Ivan Combe, American inventor (d. 2000)
- 1912 - Marcel Camus, French film director (d. 1982)
- 1914 - Norman Panama, American screenwriter (d. 2003)
- 1915 - Anthony Quinn, Mexican-born actor (d. 2001)
- 1919 - Don Cornell, American singer (d. 2004)
- 1920 - Edmund Adamkiewicz, German footballer (d. 1991)
- 1920 - Ronald Magill, British actor (d. 2007)
- 1922 - Alistair MacLean, Scottish author (d. 1987)
- 1923 - John Mortimer, English barrister and writer
- 1926 - Queen Elizabeth II of the United Kingdom
- 1927 - Gerald Flood, British actor (d. 1989)
- 1930 - Silvana Mangano, Italian actress (d. 1989)
- 1932 - Elaine May, American comedian
- 1935 - Charles Grodin, American actor
- 1935 - Thomas Kean, former Governor of New Jersey and 9/11 Commission Chairman
- 1936 - James Dobson, American evangelist
- 1938 - Ernie Maresca, American singer, songwriter and record executive
- 1939 - Helen Prejean, American writer
- 1944 - Adrian Hurley, Australian basketball coach
- 1945 - Diana Darvey, British actress, singer and dancer (d. 2000)
- 1947 - Iggy Pop, American musician (The Stooges)
- 1947 - John Weider, British rock musician (Eric Burdon and the Animals, Family)
- 1948 - Gary Condit, American politician
- 1948 - Paul Davis, American singer
- 1949 - Patti Lupone, American singer and actress
- 1951 - Tony Danza, American actor and comedian
- 1951 - Michael Hartley Freedman, American mathematician
- 1951 - Robert Gotobed, English drummer (Wire)
- 1951 - Steve Vickers, Canadian ice hockey player
- 1954 - James Morrison, American actor
- 1954 - Ebiet G. Ade, Indonesian singer
- 1956 - Phillip Longman, American demographer
- 1958 - Edward Leslie, American professional wrestler
- 1958 - Andie MacDowell, American actress
- 1958 - Michael S. Zarnock, American author/columnist/Guinness World Record Holder
- 1959 - Gene Callahan, American writer
- 1959 - Robert Smith, British musician (The Cure)
- 1959 - Jerry Only, American musician (The Misfits)
- 1959 - Michael Timmins, Canadian musician (Cowboy Junkies)
- 1960 - Michel Goulet, Canadian ice hockey player
- 1962 - Les Lancaster, American baseball player
- 1963 - Ken Caminiti, American baseball player (d. 2004)
- 1963 - Roy Dupuis, Canadian actor
- 1963 - John Cameron Mitchell, American film director
- 1964 - Ludmila Engquist, Russian-born Swedish athlete
- 1964 - Alex Baumann, Canadian Olympic swimmer
- 1965 - Ed Belfour, Canadian ice hockey player
- 1965 - Karen Foster, American model (Playboy)
- 1966 - Michael Franti, American musician
- 1969 - Robin Meade, American reporter
- 1970 - Rob Riggle, American comedian
- 1970 - Nicole Sullivan, American actress
- 1971 - Eric Mabius, American actor
- 1971 - Michael Turner, American comic book artist
- 1972 - Severina Vučković, Croatian singer
- 1972 - Gwendal Peizerat, French ice dancer
- 1977 - Jamie Salé, Canadian figure skater
- 1978 - Jukka Nevalainen, Finnish drummer (Nightwish)
- 1978 - Branden Steineckert, American drummer (Rancid, formerly of The Used)
- 1979 - Doseone, American rapper
- 1979 - James McAvoy, Scottish actor
- 1980 - Vincent Lecavalier, Canadian hockey player
- 1980 - Tony Romo, American football player
- 1981 - Stephanie Larimore, American model
- 1982 - Carnell "Cadillac" Williams, American football player
- 1983 - Paweł Brożek, Polish footballer
- 1984 - Eric Devendorf, American basketball player
- 1986 - Audra Cohen, American tennis player
- 1986 - Alexander Edler, Swedish hockey player
- 1988 - Pedro Mosquera, Spanish footballer
- 1988 - Robbie Amell, Canadian actor
- 748 - Empress Genshō of Japan (b. 680)
- 1073 - Pope Alexander II
- 1109 - Anselm of Canterbury, Archbishop of Canterbury
- 1142 - Pierre Abélard, French writer (b. 1079)
- 1329 - Frederick IV (b. 1282)
- 1509 - King Henry VII of England (b. 1457)
- 1551 - Oda Nobuhide, Japanese warlord (b. 1510)
- 1557 - Petrus Apianus, German mathematician (b. 1495)
- 1574 - Cosimo I de' Medici (b. 1519)
- 1699 - Jean Racine, French dramatist (b. 1639)
- 1701 - Asano Naganori, Japanese warlord (b. 1667)
- 1719 - Philippe de la Hire, French mathematician and historian (b. 1640)
- 1720 - Antoine Hamilton, French writer (b. 1646)
- 1722 - Robert Beverley, historian of Colonial Virginia (b. 1673)
- 1792 - Tiradentes, Brazilian revolutionary (b. 1746)
- 1793 - John Michell, English seismologist (b. 1724)
- 1815 - Joseph Winston, U.S. Congressman from North Carolina (b. 1746)
- 1825 - Johann Friedrich Pfaff, German mathemattician (b. 1765)
- 1852 - Ivan Nabokov, Russian general (b. 1787)
- 1868 - Henry James O'Farrell, Australian would-be assassin of Prince Alfred, Duke of Edinburgh
- 1910 - Mark Twain, American author and humorist (b. 1835)
- 1918 - Manfred von Richthofen, German pilot (b. 1892)
- 1924 - Eleonora Duse, Italian actress (b. 1858)
- 1930 - Robert Bridges, English poet (b. 1844)
- 1938 - Allama Iqbal, Indian philosopher and poet (b. 1877)
- 1945 - Walter Model, German field marshal (b. 1891)
- 1946 - John Maynard Keynes, English economist (b. 1883)
- 1956 - Charles MacArthur, American writer (b. 1895)
- 1965 - Edward Victor Appleton, English physicist, Nobel Prize laureate (b. 1892)
- 1971 - François "Papa Doc" Duvalier, Haitian dictator (b. 1907)
- 1973 - Arthur Fadden, thirteenth Prime Minister of Australia (b. 1894)
- 1977 - Gummo Marx, American actor and comedian (b. 1892)
- 1978 - Sandy Denny, British vocalist (b. 1947)
- 1978 - Thomas Wyatt Turner, American civil rights advocate and agricultural engineer (b. 1877)
- 1980 - Aleksandr Oparin, Russian biochemist (b. 1894)
- 1980 - Sohrab Sepehri, Persian poet and painter (b. 1928)
- 1983 - Walter Slezak, Austrian actor (b. 1902)
- 1985 - Rudi Gernreich, Austrian fashion designer (b. 1922)
- 1985 - Tancredo de Almeida Neves, Brazil banker and elected president (b. 1910)
- 1985 - Foster Hewitt, Canadian radio pioneer (b. 1902)
- 1986 - Salah Jaheen, Egyptian poet and cartoonist (b.1930)
- 1989 - Princess Dukhye of Korea (b. 1912)
- 1990 - Erté, French artist (b. 1892)
- 1991 - Willi Boskovsky, Austrian violinist and conductor (b. 1909)
- 1996 - Dzhokhar Dudaev, Chechen leader (b. 1944)
- 1996 - Jimmy the Greek, American bookie and sports broadcaster (b. 1919)
- 1999 - Charles 'Buddy' Rogers, American actor and musician (b. 1904)
- 2000 - Neal Matthews, American singer (b. 1929)
- 2003 - Nina Simone, American singer and pianist (b. 1933)
- 2004 - Mary McGrory, American journalist (b. 1918)
- 2005 - Gerry Marshall, British racing driver (b. 1941)
- 2006 - Telê Santana, Brazilian football manager (b. 1931)
- 2006 - T.K. Ramakrishnan, Indian politician (b. 1922)
- 2007 - Lobby Loyde, Australian guitarist and songwriter (b. 1941)
Holidays and observances
90 Familypedia people were born on April 21
129 Familypedia people died on April 21
128 Familypedia people were first married on April 21