April 30 is the 120th day of the year (121st in leap years) in the Gregorian calendar. There are 245 days remaining until the end of the year.
- 313 - Roman emperor Licinius unifies the entire Eastern Roman Empire under his rule.
- 711 - Islamic conquest of Hispania: Moorish troops led by Tariq ibn-Ziyad land at Gibraltar to begin their invasion of the Iberian Peninsula (Al-Andalus).
- 1006 - Supernova SN 1006, the brightest supernova in recorded history, appears in the constellation Lupus.
- 1315 - Enguerrand de Marigny is hanged on the public gallows at Montfaucon.
- 1483 - Orbital calculations suggest that on this day, Pluto moved inside Neptune's orbit until July 23, 1503.
- 1492 - Spain gives Christopher Columbus his commission of exploration.
- 1671 - Petar Zrinski, the Croatian Ban from the Zrinski family, is executed.
- 1774 - Yellow Creek massacre, British settlers (soon to be American settlers) massacre family members of Chief Logan and spark off the conflict known as Lord Dunmore's War
- 1789 - On the balcony of Federal Hall on Wall Street in New York City, George Washington takes the oath of office to become the first elected President of the United States.
- 1794 - The Battle of Boulou is fought, in which French forces defeated the Spanish under General Union.
- 1803 - Louisiana Purchase: The United States purchases the Louisiana Territory from France for $15 million, more than doubling the size of the young nation.
- 1812 - The Territory of Orleans becomes the 18th U.S. state under the name Louisiana.
- 1838 - Nicaragua declares independence from the Central American Federation.
- 1856 - Battle of Rivas, Nicaragua, against North American mercenaries.
- 1863 - Mexican forces attacked the French Foreign Legion in Hacienda Camarón, Mexico.
- 1871 - The Camp Grant Massacre takes place in Arizona Territory.
- 1894 - Coxey's Army reaches Washington, D.C. to protest the unemployment caused by the Panic of 1893.
- 1900 - Hawaii becomes a territory of the United States, with Sanford B. Dole as governor.
- 1900 - Casey Jones dies in a train wreck in Vaughn, Mississippi, while trying to make up time on the Cannonball Express.
- 1904 - The Louisiana Purchase Exposition World's Fair opens in St. Louis, Missouri.
- 1907 - Honolulu, Hawaii becomes an independent city.
- 1920 - Peru becomes a signatory to the Buenos Aires copyright treaty.
- 1925 - Automaker Dodge Brothers, Inc is sold to Dillon, Read & Company for $146 million plus $50 million for charity.
- 1927 - The Federal Industrial Institute for Women, opens in Alderson, West Virginia, as the first women's federal prison in the United States.
- 1927 - Douglas Fairbanks and Mary Pickford become the first celebrities to leave their footprints in concrete at Grauman's Chinese Theater in Hollywood.
- 1937 - The Philippines holds a plebiscite for Filipino women on whether they should be extended the right to suffrage; over 90% would vote in the affirmative.
- 1938 - The animated cartoon short Porky's Hare Hunt debuts in movie theaters, introducing Happy Rabbit.
- 1938 - The first televised FA Cup Final takes place between Huddersfield Town and Preston North End.
- 1939 - The 1939 New York World's Fair opens.
- 1939 - RCA owned NBC begins regularly scheduled television service from its New York station with the opening ceremonies of the 1939 New York World's Fair broadcast.
- 1939 - Franklin D. Roosevelt becomes the first U.S. President to appear on television during the World Fair's opening ceremonies broadcast.
- 1943 - World War II: Operation Mincemeat: The submarine HMS Seraph surfaces in the Mediterranean Sea off the coast of Spain to deposit a dead man planted with false invasion plans and dressed as a British military intelligence officer.
- 1945 - World War II: Fuehrerbunker: Adolf Hitler and Eva Braun commit suicide after being married for one day. Soviet soldiers raise the red flag over the Reichstag building.
- 1947 - In Nevada, the Boulder Dam is renamed Hoover Dam a second time.
- 1948 - In Bogotá, Colombia, the Organization of American States is established.
- 1956 - Former Vice President and Senator Alben Barkley dies during a speech in Virginia. He collapsed after proclaiming " I would rather be a servant in the house of the lord than sit in the seats of the mighty."
- 1973 - Watergate Scandal: U.S. President Richard Nixon announces that top White House aids H.R. Haldeman, John Ehrlichman, and others have resigned.
- 1975 - Fall of Saigon: Communist forces gain control of Saigon. The Vietnam War formally ends with the unconditional surrender of South Vietnamese president Duong Van Minh.
- 1980 - Accession of Queen Beatrix of the Netherlands.
- 1988 - Her Majesty Queen Elizabeth II officially opens World Expo '88, Brisbane, Australia.
- 1993 - The World Wide Web is born at CERN.
- 1993 - Virgin Radio broadcasts for the first time in the United Kingdom.
- 1995 - U.S. President Bill Clinton became the first President to visit Northern Ireland.
- 1999 - Cambodia joins the Association of Southeast Asian Nations (ASEAN) bringing the total members to 10.
- 2001 - The Mitchell Report on the Arab-Israeli conflict is published.
- 2002 - A referendum in Pakistan overwhelmingly approves the Presidency of Pervez Musharraf for another five years.
- 2004 - U.S. media release graphic photos of American soldiers abusing and sexually humiliating Iraqi prisoners at Abu Ghraib prison.
- 2008 - Two skeletal remains found near Ekaterinburg, Russia were confirmed by Russian scientists to be the remains of Alexei Nikolaevich, Tsarevich of Russia and one of his sisters.
- 1245 - King Philip III of France (d. 1285)
- 1553 - Louise de Lorraine-Vaudémont, queen of France (d. 1601)
- 1623 - François de Laval, first bishop of New France (d. 1708)
- 1651 - Jean-Baptiste de la Salle, French educational reformer, Catholic saint (d. 1719)
- 1662 - Queen Mary II of England (d. 1694)
- 1664 - François Louis, Prince of Conti, French general (d. 1709)
- 1710 - Johann Kaspar Basselet von La Rosée, Bavarian general (d. 1795)
- 1721 - Roger Sherman, American statesman (d. 1793)
- 1723 - Mathurin Jacques Brisson, French naturalist (d. 1806)
- 1770 - David Thompson, Canadian explorer (d. 1857)
- 1777 - Carl Friedrich Gauss, German mathematician (d. 1855)
- 1803 - Albrecht Graf von Roon, Prime Minister of Prussia (d. 1879)
- 1812 - Kaspar Hauser, German mystery boy (d. 1833)
- 1829 - Ferdinand von Hochstetter, Austrian geologist (d. 1884)
- 1857 - Eugen Bleuler, Swiss psychiatrist (d. 1940)
- 1864 - Juhan Liiv, Estonian poet (d. 1913)
- 1865 - Max Nettlau, German anarchist (d. 1944)
- 1869 - Hans Poelzig, German architect (d. 1936)
- 1870 - Franz Lehár, Austrian composer (d. 1948)
- 1874 - Cyriel Verschaeve, Flemish clergyman (d. 1949)
- 1876 - Orso Mario Corbino, Italian physicist (d. 1937)
- 1877 - Alice B. Toklas, American companion of Gertrude Stein (d. 1967)
- 1883 - Jaroslav Hašek, Czech novelist (d. 1923)
- 1893 - Joachim von Ribbentrop, Nazi foreign minister (d. 1946)
- 1895 - Philippe Panneton, French Canadian physician, diplomat and writer (d. 1960)
- 1896 - Hans List, Austrian inventor (d. 1996)
- 1897 - Humberto Mauro, Brazillina director and screenwriter (d. 1983)
- 1901 - Simon Kuznets, Ukrainian-born economist, Nobel laureate (d. 1985)
- 1902 - Theodore Schultz, American economist, Nobel laureate (d. 1998)
- 1908 - Eve Arden, American actress (d. 1990)
- 1908 - Bjarni Benediktsson, Icelandic foreign and later prime minister (d. 1970)
- 1909 - Queen Juliana of the Netherlands (d. 2004)
- 1909 - F. E. McWilliam,Irish sculptor (d. 1992)
- 1916 - Claude Shannon, American engineer and mathematician (d. 2001)
- 1916 - Robert Shaw, American conductor (d. 1999)
- 1920 - Duncan Hamilton, British racing driver (d. 1994)
- 1923 - Percy Heath, American jazz musician (Modern Jazz Quartet) (d. 2005)
- 1923 - Al Lewis, American actor (d. 2006)
- 1923 - Francis Tucker, South African Rally Driver (d. 2008)
- 1925 - Corinne Calvet, French actress (d. 2001)
- 1925 - Johnny Horton, American musician (d. 1960)
- 1926 - Cloris Leachman, American actress
- 1928 - Hugh Hood, Canadian author (d. 2000)
- 1930 - Felix Guattari, French philosopher and social theorist, (d. 1992)
- 1933 - Dickie Davies, British television presenter
- 1933 - Willie Nelson, American musician
- 1934 - Jerry Lordan, English composer and singer (d. 1995)
- 1938 - Juraj Jakubisko, Slovak film director
- 1938 - Gary Collins, American actor
- 1938 - Larry Niven, American author
- 1940 - Burt Young, American actor
- 1941 - Johnny Farina, American musician and composer (Santo & Johnny)
- 1943 - Frederick Chiluba, former Zambian president (1991-2001)
- 1943 - Bobby Vee, American singer
- 1944 - Jill Clayburgh, American actress
- 1945 - Annie Dillard, American writer
- 1945 - Michael Smith, American astronaut (d. 1986)
- 1946 - King Carl XVI Gustaf of Sweden
- 1946 - Don Schollander, American swimmer
- 1946 - Bill Plympton, American animator
- 1947 - Leslie Grantham, English actor
- 1947 - Finn Kalvik, Norwegian singer
- 1947 - Mats Odell, Swedish politician
- 1947 - Tom Køhlert, Danish footballer
- 1948 - Perry King, American actor
- 1949 - Phil Garner, baseball manager
- 1949 - António Guterres, Prime Minister of Portugal
- 1952 - Jacques Audiard, French film director
- 1953 - Merrill Osmond, American musician (The Osmonds)
- 1954 - Jane Campion, New Zealand film director
- 1955 - Nicolas Hulot, French journalist
- 1956 - Jorge Chaminé, Portuguese baritone
- 1956 - Lars von Trier, Danish film director
- 1957 - Aviva Chomsky, American historian, daughter of Noam Chomsky
- 1958 - Charles Berling, French actor, director and screenwriter
- 1959 - Paul Gross, Canadian actor, director, and writer
- 1959 - Stephen Harper, Prime Minister of Canada
- 1959 - W. Thomas Smith, Jr, American author and columnist
- 1960 - Kerry Healey, American politician
- 1960 - David Miscavige, American cult leader
- 1961 - Isiah Thomas, American basketball player
- 1963 - Michael Waltrip, American race car driver
- 1964 - Ian Healy, Australian cricketer
- 1964 - Barrington Levy, Jamaican musician
- 1965 - Adrian Pasdar, American actor
- 1966 - Jeff Brown, Canadian ice hockey player
- 1967 - Steven Mackintosh, British actor
- 1969 - Paulo Jr., Brazilian musician (Sepultura)
- 1969 - Warren Defever, American musician, composer
- 1970 - Ken Stanton, American Radio Personality
- 1971 - John Boyne, Irish novelist
- 1971 - Darren Emerson, English DJ (Underworld)
- 1973 - Akon, American R&B Singer
- 1975 - Elliott Sadler, American race car driver
- 1975 - Mike Chat, American actor
- 1975 - Johnny Galecki, American actor
- 1976 - Amanda Palmer, American musician (The Dresden Dolls)
- 1977 - Jeannie Haddaway, American politician
- 1977 - Pell James, American actress
- 1979 - Gerardo Torrado, Mexican footballer
- 1981 - John O'Shea, Irish footballer
- 1981 - Emma Pierson, British actress
- 1982 - Lloyd Banks, American rapper
- 1982 - Kirsten Dunst, American actress
- 1982 - Cleo Higgins, British singer and actress
- 1982 - Andrew Seeley, Canadian actor and singer
- 1983 - Tatjana Hüfner, German luger
- 1983 - Troy Williamson, American football player
- 1983 - Yamini, Tamil Singer
- 1984 - Shawn Daivari, Persian-American professional wrestler and manager
- 1985 - Ashley Alexandra Dupré, American singer and call girl
- 1987 - Alipate Carlile, Australian rules footballer
- 1987 - Nikki Webster, Australian entertainer
- 1987 - Rohit Sharma, Indian cricketer
- 65 - Lucan, Roman poet (b. 39)
- 1063 - Emperor Renzong of China (b. 1010)
- 1131 - Adjutor, Roman Catholic Saint
- 1341 - John III, Duke of Brittany (b. 1285)
- 1439 - Richard de Beauchamp, 13th Earl of Warwick, English military leader (b. 1382)
- 1524 - Pierre Terrail, seigneur de Bayard, French soldier (b. 1473)
- 1544 - Thomas Audley, 1st Baron Audley of Walden, Lord Chancellor of England
- 1555 - Pope Marcellus II (b. 1501)
- 1632 - King Sigismund I of Sweden (b. 1561)
- 1632 - Johan Tzerclaes, Count of Tilly, Bavarian general (b. 1559)
- 1642 - Dmitry Pozharsky, Russian prince (b. 1578)
- 1660 - Petrus Scriverius, Dutch writer (b. 1576)
- 1655 - Eustache Le Sueur, French painter (b. 1617)
- 1696 - Robert Plot, British naturalist (b. 1640)
- 1712 - Philipp van Limborch, Dutch Protestant theologian (b. 1633)
- 1736 - Johann Albert Fabricius, German classical scholar and bibliographer (b. 1668)
- 1758 - François d'Agincourt, French composer (b. 1684)
- 1792 - John Montagu, supposed inventor of the sandwich (b. 1718)
- 1795 - Jean-Jacques Barthélemy, French writer and numismatist (b. 1716)
- 1841 - Peter Andreas Heiberg, Danish author and philologist (b. 1758)
- 1847 - Archduke Charles of Austria, Austrian general (b. 1771)
- 1863 - Jean Danjou, French foreign legion captain (b. 1828)
- 1865 - Robert Fitzroy, English admiral and meteorologist (b. 1805)
- 1875 - Jean Frederic Waldeck, French explorer, lithographer, and cartographer (b. 1766)
- 1883 - Édouard Manet, French painter (b. 1832)
- 1900 - Casey Jones, American train engineer (b. 1863)
- 1903 - Emily Stowe, Canadian physician and suffragist (b. 1831)
- 1936 - Alfred Edward Housman, English poet (b. 1859)
- 1943 - Otto Jespersen, Danish philologist (b. 1860)
- 1943 - Beatrice Webb, British economist (b. 1858)
- 1945 - Eva Braun, Adolf Hitler's new wife (b. 1912)
- 1945 - Adolf Hitler, Austrian dictator of Nazi Germany (suicide) (b. 1889)
- 1956 - Alben W. Barkley, Vice President of the United States (b. 1877)
- 1970 - Inger Stevens, Swedish actress (b. 1934)
- 1973 - Václav Renč, Czech poet, dramatist and translator (b. 1911)
- 1974 - Agnes Moorehead, American actress (b. 1900)
- 1980 - Luis Muñoz Marín, Puerto Rican poet, journalist, and politician (b. 1898)
- 1982 - Lester Bangs, American music journalist, author, and musician (b. 1949)
- 1983 - George Balanchine, Russian-born dancer and choreographer (b. 1904)
- 1983 - Muddy Waters, American musician (b. 1915)
- 1985 - George Pravda, Czechoslovakian actor (b. 1918)
- 1989 - Yi, Bang-ja, Crown Princess of Korea (b. 1901)
- 1989 - Sergio Leone, Italian filmmaker (b. 1929)
- 1993 - Tommy Caton, English footballer (b. 1962)
- 1994 - Roland Ratzenberger, Austrian race car driver (b. 1960)
- 1995 - Maung Maung Kha, Prime minister of Burma (b. 1920)
- 1996 - David Opatoshu, American actor (b. 1918)
- 1998 - Nizar Qabbani, Syrian poet (b. 1926)
- 2002 - Charlotte von Mahlsdorf, founder of the Gründerzeit Museum in Berlin-Mahlsdorf. (b. 1928)
- 2003 - Peter 'Possum' Bourne, New Zealand race car driver (b. 1956)
- 2003 - Wim van Est, Dutch cyclist (b. 1923)
- 2003 - Mark Berger, University of Kentucky professor (b. 1955)
- 2005 - Ron Todd, TGWU General Secretary (1985 - 1992) (b. 1927)
- 2006 - Lawrence Patrick, Biomechanics Professor, crash test subject
- 2006 - Pramoedya Ananta Toer, Indonesian novelist
- 2007 - Grégory Lemarchal, French singer (b. 1983)
- 2007 - Kevin Mitchell, American football player (b. 1971)
- 2007 - Tom Poston, American actor (b. 1921)
- 2007 - Gordon Scott, American actor (b. 1927)
- 2007 - Zola Taylor, American singer (b. 1938)
- 2008 - John Cargher, Australian radio broadcaster (b. 1919)
in the Roman Catholic Church:
