May 15 is the 135th day of the year (136th in leap years) in the Gregorian calendar. There are 230 days remaining until the end of the year.
- 1252 - Pope Innocent IV issues the papal bull ad exstirpanda, which authorizes, but also limits, the torture of heretics in the Medieval Inquisition.
- 1514 - Jodocus Badius Ascensius publishes Christiern Pedersen's Latin version of Saxo’s Gesta Danorum, the oldest known version of that work.
- 1525 - The battle of Frankenhausen ends the Peasants' War.
- 1567 - Mary Queen of Scots marries James Hepburn, Earl of Bothwell, her third husband.
- 1602 - Bartholomew Gosnold becomes the first European to see Cape Cod.
- 1618 - Johannes Kepler confirms his previously rejected discovery of the third law of planetary motion (he first discovered it on March 8 but soon rejected the idea after some initial calculations were made).
- 1701 - The War of the Spanish Succession begins.
- 1718 - James Puckle, a London lawyer, patents the world's first machine gun.
- 1756 - The Seven Years' War begins when England declares war on France.
- 1776 - American Revolution: the Virginia Convention instructs its Continental Congress delegation to propose a resolution of independence from Great Britain, paving the way for the United States Declaration of Independence.
- 1791 - Maximilien Robespierre proposes the Self-denying Ordinance.
- 1792 - War of the First Coalition: France declares war on Kingdom of Sardinia.
- 1793 - Diego Marín Aguilera flies a glider for "about 360 meters", at a height of 5-6 meters, during one of the first attempted flights.
- 1796 - First Coalition: Napoleon enters Milan in triumph.
- 1800 - George III survives two assassination attempts in one day.
- 1811 - Paraguay declares independence from Spain.
- 1817 - Opening of the first private mental health hospital in the United States, the Asylum for the Relief of Persons Deprived of the Use of Their Reason (now Friends Hospital) in Philadelphia, Pennsylvania.
- 1836 - Francis Baily observes "Baily's beads" during an annular eclipse.
- 1849 - Troops of the Two Sicilies take Palermo and crush the republican government of Sicily.
- 1851 - Rama IV is crowned King of Thailand.
- 1858 - Opening of the present Royal Opera House in Covent Garden, London.
- 1862 - President Abraham Lincoln signs a bill into law creating the United States Bureau of Agriculture. it is later renamed the United States Department of Agriculture.
- 1864 - American Civil War: Battle of Resaca, Georgia ends.
- 1864 - American Civil War: Battle of New Market, Virginia – students from the Virginia Military Institute fight alongside the Confederate Army to force Union General Franz Sigel out of the Shenandoah Valley.
- 1869 - Woman's suffrage: in New York, Susan B. Anthony and Elizabeth Cady Stanton form the National Woman's Suffrage Association.
- 1891 - Rerum Novarum, the first document of the Catholic Social Teaching tradition, is published by Pope Leo XIII.
- 1897 - The Greek army retreats with heavy losses in the Greco-Turkish War.
- 1905 - Las Vegas, Nevada, is founded when 110 acres (0.4 km²), in what later would become downtown, are auctioned off.
- 1910 - The last time a major earthquake happened on the Elsinore Fault Zone.
- 1911 - The United States Supreme Court declares Standard Oil to be an "unreasonable" monopoly under the Sherman Antitrust Act and orders the company to be broken up.
- 1911 - The Georgios Averof cruiser is bought by Greece.
- 1914 - Bolivia becomes a signatory to the Buenos Aires copyright treaty.
- 1918 - The Finnish Civil War ends.
- 1919 - The Winnipeg General Strike begins. By 11:00 a.m., almost the whole working population of Winnipeg, Manitoba had walked off the job.
- 1919 - Greek invasion of İzmir. During the invasion, the Greek army kills or wounds 350 Turks. The responsible are punished by the Greek Commander Aristides Stergiades. Hasan Tahsin fires the first shot of the Turkish War of Independence.
- 1920 - Council of Lithuania adjourns as the newly elected Constituent Assembly of Lithuania meets for the first time in Kaunas.
- 1928- Mickey Mouse premiered in his first cartoon, Plane Crazy
- 1929 - A fire at the Cleveland Clinic in Cleveland, Ohio kills 123.
- 1932 - The May 15 Incident: in an attempted Coup d'état, the Prime Minister of Japan Inukai Tsuyoshi is killed.
- 1934 - Kārlis Ulmanis establishes an authoritarian government in Latvia.
- 1935 - The Moscow Metro is opened to public.
- 1936 - Amy Johnson arrives back in England after a record-breaking return flight to Cape Town
- 1940 - USS Sailfish (SS-192) recomisioned, origionaly the Squalus.
- 1940 - World War II: After fierce fighting, the poorly trained and equipped Dutch troops surrender to Germany, marking the beginning of five years of occupation.
- 1940 - McDonald's opens its first restaurant in San Bernardino, California.
- 1941 - Baseball player Joe DiMaggio of the New York Yankees starts his record-breaking 56-game hitting streak.
- 1942 - World War II: in the United States, a bill creating the Women's Army Auxiliary Corps (WAAC) is signed into law.
- 1943 - Joseph Stalin dissolves the Comintern (or Third International).
- 1945 - World War II: The final skirmish in Europe is fought near Prevalje, Slovenia.
- 1948 - Following the demise of the British Mandate of Palestine, Egypt, Transjordan, Lebanon, Syria, Iraq and Saudi Arabia attack Israel.
- 1951 - The Polish cultural attache in Paris, Czesław Miłosz, asks the French government for political asylum.
- 1955 - The Austrian Independence Treaty is signed.
- 1955 - The first ascent of Makalu, the world's fifth highest mountain.
- 1957 - At Malden Island in the Pacific, Britain tests its first hydrogen bomb in Operation Grapple. The device fails to detonate properly.
- 1958 - The Soviet Union launches Sputnik 3.
- 1960 - The Soviet Union launches Sputnik 4.
- 1963 - Project Mercury: The launch of the final Mercury mission, Mercury-Atlas 9 with astronaut L. Gordon Cooper on board. He becomes the first American to spend more than a day in space.
- 1970 - President Richard Nixon appoints Anna Mae Hays and Elizabeth P. Hoisington the first female United States Army Generals.
- 1970 - Philip Lafayette Gibbs and James Earl Green are killed at Jackson State University by police during student protests.
- 1972 - The island of Okinawa, under U.S. military governance since its conquest in 1945, reverts to Japanese control.
- 1972 - In Laurel, Maryland, Arthur Bremer shoots and paralyzes Alabama Governor George Wallace while he is campaigning to be become President.
- 1974 – Ma'alot massacre: A total of 31 people, including hostage takers, are killed.
- 1987 - The Soviet Union launches the Polyus prototype orbital weapons platform. It fails to reach orbit.
- 1988 - Soviet war in Afghanistan: After more than eight years of fighting, the Red Army begins its withdrawal from Afghanistan.
- 1990 - Portrait of Doctor Gachet by Vincent van Gogh is sold for a record $82.5 million, the most expensive painting at the time.
- 1991 - Edith Cresson becomes France's first female prime minister.
- 1997 - The United States government acknowledges the existence of the "Secret War" in Laos and dedicates the Laos Memorial in honor of Hmong and other "Secret War" veterans.
- 2008 - California becomes the second U.S. state after Massachusetts in 2004 to legalize same-sex marriage after the state's own Supreme Court rules a previous ban unconstitutional.
- 1567 - (baptism) Claudio Monteverdi, Italian composer (d. 1643)
- 1608 - René Goupil, French Catholic missionary (Canadian Martyrs) (d. 1642)
- 1720 - Maximilian Hell, Slovakian astronomer (d. 1792)
- 1749 - Levi Lincoln, Sr., American revolutionary, statesman, politician, and acting Governor of Massachusetts (d. 1820)
- 1773 - Prince Klemens Wenzel von Metternich, Austrian statesman (d. 1859)
- 1786 - General Dimitris Plapoutas, a Revolutionary in the Greek War of Independence (d. 1864)
- 1817 - Debendranath Tagore, Indian religious reformer (d. 1905)
- 1848 - Viktor Vasnetsov, Russian painter (d. 1926)
- 1856 - L. Frank Baum, American author (d. 1919)
- 1857 - Williamina Fleming, Scottish-born astronomer (d. 1911)
- 1859 - Pierre Curie, French physicist, Nobel Prize laureate (d. 1906)
- 1862 - Arthur Schnitzler, Austrian dramatist and narrator (d. 1931)
- 1890 - Katherine Anne Porter, American author (d. 1980)
- 1891 - Mikhail Bulgakov, Russian writer (d. 1940)
- 1891 - Fritz Feigl, Austria-born chemist (d. 1971)
- 1892 - Jimmy Wilde, boxer (d. 1969)
- 1895 - William D. Byron, U.S. Congressman (d. 1941)
- 1898 - Arletty, French model and actress (d. 1992)
- 1899 - Jean-Etienne Valluy, French general (d. 1970)
- 1901 - Xavier Herbert, Australian author (d. 1984)
- 1901 - Luis Monti, Argentine-Italian footballer (d. 1983)
- 1902 - Richard J. Daley, Mayor of Chicago (d. 1976)
- 1903 - Maria Reiche, German-born mathematician and archaeologist (d. 1998)
- 1905 - Joseph Cotten, American actor (d. 1994)
- 1907 - Sukhdev Thapar, Indian freedom fighter (d. 1931)
- 1909 - James Mason, English actor (d. 1984)
- 1910 - Constance Cummings, British actress (d. 2005)
- 1911 - Max Frisch, Swiss author (d. 1991)
- 1911 - Herta Oberheuser, Nazi doctor (d. 1978)
- 1912 - Arthur Berger, American composer (d. 2003)
- 1914 - Turk Broda, ice hockey goaltender (d. 1972)
- 1914 - Tenzing Norgay, (adopted birthdate) Nepalese Sherpa who accompanied Edmund Hillary to the top of Mount Everest (d. 1986)
- 1915 - Hilda Bernstein, English-born South African author, artist, and activist (d. 2006)
- 1915 - Mario Monicelli, Italian director and screenwriter
- 1915 - Paul Samuelson, American economist, Nobel Prize laureate
- 1915 - Gus Viseur, French button accordionist (d. 1974)
- 1918 - Eddy Arnold, American country music singer (d. 2008)
- 1918 - Joseph Wiseman, Canadian actor
- 1922 - Jakucho Setouchi, Japanese writer and Buddhist nun
- 1923 - Richard Avedon, American photographer (d. 2004)
- 1923 - John Lanchbery, English composer (d. 2003)
- 1923 - Johnny Walker, Indian actor (d. 2003)
- 1924 - Maria Koepcke, German ornithologist (d. 1971)
- 1926 - Anthony Shaffer, English playwright (d. 2001)
- 1926 - Peter Shaffer, English playwright
- 1930 - Jasper Johns, American painter
- 1931 - Ken Venturi, American golfer
- 1935 - Utah Phillips, American labor organizer and folk singer
- 1936 - Anna Maria Alberghetti, Italian-born actress
- 1936 - Wavy Gravy, American clown and activist
- 1936 - Ralph Steadman, British cartoonist
- 1936 - Paul Zindel, American writer (d. 2003)
- 1937 - Madeleine Albright, U.S. Secretary of State
- 1937 - Trini López, American musician
- 1938 - Mireille Darc, French actress
- 1938 - Diane Nash, American 1960s Civil Rights Movement leader
- 1938 - Lenny Welch, American singer
- 1939 - Dorothy Shirley, British athlete
- 1940 - Lainie Kazan, American actress and singer
- 1940 - Roger Ailes, American businessman
- 1940 - Don Nelson, American basketball coach, currently of the Golden State Warriors
- 1941 - K.T. Oslin, American musician
- 1942 - Jusuf Kalla, vice- president of Indonesia and Chairman of the Golkar Party.
- 1942 - Doug Lowe, 35th Premier of Tasmania
- 1944 - Ulrich Beck, German sociologist
- 1944 - Bill Alter, Missouri State Senator
- 1945 - Lasse Berghagen, Swedish singer
- 1945 - Duarte Pio, Duke of Braganza, heir to the Portuguese crown
- 1947 - Graeham Goble, Australian musician, singer/songwriter, and record producer (co-founding member of Little River Band)
- 1948 - Brian Eno, English musician and record producer
- 1948 - Kathleen Sebelius, American politician, governor of Kansas
- 1948 - Yutaka Enatsu, Japanese professional baseball pitcher
- 1950 - Nicholas Hammond, American actor
- 1951 - Frank Wilczek, American physicist, Nobel Prize laureate
- 1952 - Chazz Palminteri, American actor, writer and director
- 1953 - George Brett, American baseball player
- 1953 - Mike Oldfield, English composer
- 1954 - Robert P. Harrison, American thinker
- 1955 - Lee Horsley, American actor
- 1956 - Dan Patrick, American sportscaster
- 1957 - Juan José Ibarretxe, Basque Lehendakari (Prime Minister)
- 1957 - Kevin Von Erich, American professional wrestler
- 1958 - Ron Simmons, American professional wrestler
- 1959 - Andrew Eldritch, English singer and songwriter (The Sisters of Mercy)
- 1959 - Kaokor Galaxy, Thai boxer
- 1959 - Luis Perez-Sala, Spanish racing driver
- 1960 - Rob Bowman, American film director
- 1961 - Katrin Cartlidge, British actress (d. 2002)
- 1961 - Melle Mel, American musician
- 1965 - Raí, Brazilian footballer
- 1966 - Pete Wiggs, English musician (Saint Etienne)
- 1967 - Madhuri Dixit, Indian actress
- 1967 - John Smoltz, baseball player
- 1968 - Cecilia Malmström, Swedish politician
- 1968 - Seth Putnam, American musician
- 1969 - Hideki Irabu, Japanese baseball player
- 1969 - Emmitt Smith, American football player
- 1969 - Asalah Nasri, Syrian singer
- 1970 - Martin Rossiter, Welsh Musician
- 1970 - Frank de Boer, Dutch football player
- 1970 - Ronald de Boer, Dutch football player
- 1970 - Desmond Howard, American football player
- 1970 - Rod Smith, American football player
- 1971 - Phil Pfister, American strength athlete
- 1972 - David Charvet, French actor
- 1974 - Vassilis Kikilias, Greek basketball player
- 1974 - Ahmet Zappa, American musician
- 1974 - Shiney Ahuja, Indian actor
- 1975 - Peter Iwers, Swedish Musician
- 1975 - Ray Lewis, American football player
- 1976 - Adolfo Bautista, Mexican footballer
- 1976 - Torraye Braggs, American basketball player
- 1976 - Jacek Krzynówek, Polish footballer
- 1976 - Ryan Leaf, American football player
- 1976 - Tyler Walker, baseball player
- 1978 - Amy Chow, American gymnast
- 1978 - Dwayne DeRosario, Canadian footballer
- 1978 - Caroline Dhavernas, Canadian actress
- 1978 - Edu, Brazilian footballer
- 1978 - David Krumholtz, American actor
- 1978 - Krissy Taylor, American model (d. 1995)
- 1980 - Josh Beckett, American baseball player
- 1980 - Rocky Marquette, American actor
- 1981 - Patrice Evra, French-Senegalese footballer
- 1981 - Justin Morneau, Canadian baseball player
- 1981 - Zara Phillips, British royal and eventer
- 1981 - Jamie-Lynn Sigler, American actress
- 1982 - Alex Breckenridge, American actress
- 1982 - Veronica Campbell-Brown, Jamaican athlete
- 1982 - Segundo Castillo, Ecuadorian footballer
- 1982 - Tatsuya Fujiwara, Japanese actor
- 1982 - Jessica Sutta, American dancer, singer and actress (The Pussycat Dolls)
- 1983 - Devin Bronson, American guitarist (Avril Lavigne)
- 1984 - Sérgio Jimenez, Brazilian racing driver
- 1985 - Cristiane, Brazilian footballer
- 1986 - Matías Fernández, Chilean footballer
- 1986 - Adam Moffat, Scottish football player
- 1986 - Kyle Loza,Freestyle Motocross Rider
- 1987 - Ersan İlyasova, Turkish basketball player
- 1987 - Jennylyn Mercado, Filipina actress and singer
- 1987 - Andy Murray, Scottish tennis player
- 1990 - Joe Mattock, English football player
- 1995 - Ksenia Sitnik, Belarusian singer
- 913 - Hatto I, Archbishop of Mainz
- 1036 - Emperor Go-Ichijō of Japan (b. 1008)
- 1157 - Yury Dolgoruky, Russian prince
- 1174 - Nur ad-Din, ruler of Syria (b. 1118)
- 1381 - Eppelein von Gailingen, German robber baron
- 1470 - Charles VIII of Sweden (b. 1409)
- 1585 - Niwa Nagahide, Japanese warlord (b. 1535)
- 1591 - Dmitry Ivanovich, Tsarevich (b. 1582)
- 1609 - Giovanni Croce, Italian composer (b. 1557)
- 1634 - Hendrick Avercamp, Dutch painter (b. 1585)
- 1698 - Marie Champmeslé, French actress (b. 1642)
- 1699 - Edward Petre, English Jesuit and privy councilor (b. 1631)
- 1714 - Roger Elliott, British general and Governor of Gibraltar
- 1740 - Ephraim Chambers, English encyclopaedist (b. 1680)
- 1760 - Alaungpaya, King of Burma (b. 1711)
- 1773 - Alban Butler, English Catholic priest and writer (b. 1710)
- 1782 - Marquis of Pombal, Prime Minister of Portugal (b. 1699)
- 1879 - Gottfried Semper, German architect (b. 1803)
- 1886 - Emily Dickinson, American poet (b. 1830)
- 1924 - Paul-Henri-Benjamin d'Estournelles de Constant, French diplomat, recipient of the Nobel Peace Prize (b. 1852)
- 1935 - Kazimir Malevich, Polish/Ukrainian artist (b. 1878)
- 1937 - Phillip Snowden, British politician (b. 1864)
- 1940 - Menno ter Braak, Dutch author and polemicist (b. 1902)
- 1945 - Charles Williams, UK writer (b. 1886)
- 1948 - Edward Flanagan, American priest and founder of Boys Town (b. 1886)
- 1954 - William March, American writer (b. 1893)
- 1956 - Austin Osman Spare, English artist and magician (b. 1886)
- 1964 - Vladko Maček, Kingdom of Yugoslavia deputy prime minister (b. 1879)
- 1967 - Edward Hopper, American painter (b. 1882)
- 1971 - Tyrone Guthrie, English director, producer, and writer (b. 1900)
- 1978 - Sir Robert Menzies, twelfth Prime Minister of Australia (b. 1894)
- 1982 - Gordon Smiley, American race car driver (b. 1946)
- 1984 - Francis Schaeffer, American theologian, philosopher, and pastor (b. 1912)
- 1986 - Theodore White, American writer (b. 1915)
- 1986 - Elio de Angelis, Italian race car driver (b. 1958)
- 1989 - Johnny Green, American songwriter (b. 1908)
- 1991 - Andreas Floer, German mathematician (b. 1956)
- 1991 - Ronald Lacey, English actor (b. 1935)
- 1992 - Jovy Marcelo, Filipino race car driver (b. 1965)
- 1993 - Salah Ahmed Ibrahim, Sudanese writer, poet, and diplomat (b. 1933)
- 1994 - Gilbert Roland, Mexican actor (b. 1905)
- 1995 - Eric Porter, British actor (b. 1928)
- 1996 - Charles B. Fulton, American jurist (b. 1910)
- 1998 - Earl Manigault, American basketball player (b. 1944)
- 2003 - June Carter Cash, American musician and singer (b. 1929)
- 2003 - George Francis, British gangster (b. 1940)
- 2005 - Alan B. Gold, Quebec Chief Justice (b. 1917)
- 2007 - Jerry Falwell, American evangelist (b. 1933)
- 2007 - Yolanda King, American actress and activist, daughter of Martin Luther King, Jr. (b. 1955)
- 2008 - Alexander Courage, composer of original Star Trek theme (b. 1919)
- 2008 - Tommy Burns, Scottish footballer (b. 1956)
- 2008 - Robert Dunlop, Northern Irish motorcycle racer, younger brother of Joey Dunlop (b. 1960)
In the Roman Catholic Church:
In the Coptic Church
