1903

January

 * January 1 – Edward VII is proclaimed Emperor of India.
 * January 19 – The first west–east transatlantic radio broadcast is made from the United States to England (the first east–west broadcast having been made in 1901).

February

 * February 11 – The Oxnard strike of 1903 becomes the first time in U.S. history that a labor union is formed from members of different races.
 * February 15 – Morris and Rose Michtom introduce the first teddy bear in the United States.
 * February 17 – El Yunque National Forest in Puerto Rico becomes part of the United States National Forest System as the Luquillo Forest Reserve.
 * February 23 – Cuba leases Guantánamo Bay to the United States "in perpetuity".

March

 * March 2 – In New York City, the Martha Washington Hotel, the first hotel exclusively for women, opens.
 * March 3 – The British Admiralty announces plans to build a naval base at Rosyth.
 * March 5 – The Ottoman Empire and the German Empire sign an agreement to build the Constantinople–Baghdad Railway.
 * March 12 – The University of Puerto Rico is founded.
 * March 14 – The Hay–Herrán Treaty, granting the United States the right to build the Panama Canal, is ratified by the United States Senate. The Colombian Senate later rejects the treaty.

April

 * April 26 – Atletico Madrid, as well known for professional football club in Spain, officially founded.
 * April 29 – A 30-million-m3 landslide kills 70-90 in Frank, Alberta.
 * April 29 – A strong earthquake destroys the town of Melazhgerd, Van Province, Armenia. Over 2,000 people killed.

May

 * May 4 – The leading Macedonian Bulgarian revolutionary Gotse Delchev is killed in a skirmish with the Turkish army.
 * May 18 – The port of Burgas, Bulgaria opens.
 * May 22 – The White Star Liner, SS Ionic, is launched.
 * May 24 – The Paris–Madrid race for automobiles begins, during which at least eight people are killed.
 * May 29 (O.S.) – In the May coup d'état, Alexander I, King of Serbia, and Queen Draga, are assassinated in Belgrade by the Black Hand (Crna Ruka) organization.

June

 * June 11 – Serbian King Alexander Obrenović and Queen Draga are assassinated.
 * June 14 – The town of Heppner, Oregon, is nearly destroyed by a cloud burst that resulted in a flash flood that kills an estimated 238 people.
 * June 27 – 19-year-old American socialite Aida de Acosta becomes the first woman to fly a powered aircraft solo when she pilots Santos-Dumont's motorized dirigible, “No. 9”, from Paris to Château de Bagatelle in France.

July

 * July 1–July 19 – First Tour de France bicycle race, won by Maurice Garin.
 * July 7 – The British take over the Fulani Empire.
 * July 23 – Dr. Ernst Pfenning of Chicago becomes the first owner of a Ford Model A.
 * July 29 – Explosion of a United States Cartridge Company magazine destroys 70 homes killing 22 residents of Tewksbury, Massachusetts.
 * July 30–August 23 (July 17–August 10, O.S.) – Second Congress of the All-Russian Social Democratic Labour Party held in exile in Brussels, transferring to London.

August

 * August 2 – The Ilinden–Preobrazhenie Uprising, organized by the Secret Macedonian-Adrianople Revolutionary Organization, breaks out in the Ottoman provinces of Macedonia and Adrianople.
 * August 4 – Pope Pius X succeeds Pope Leo XIII as the 257th pope.
 * August 10 – Paris Métro train fire takes place.
 * August 25 – The Judiciary Act is passed in the Australian parliament.

September

 * September 11 – The first stock car event is held at the Milwaukee Mile.
 * September 14 – Joseph Chamberlain resigns as British Colonial Secretary, in order to campaign publicly for Imperial Preference.
 * September 15 – Grêmio Foot-Ball Porto Alegrense is founded in Porto Alegre, Brazil
 * September 24 – Edmund Barton steps down as Prime Minister of Australia and is succeeded by Alfred Deakin.
 * September 27 – The Wreck of the Old 97 Fast Mail train at Stillhouse Trestle near Danville, Virginia kills 11 people and inspires a ballad.
 * September 29 – Prussia becomes the first locality to require mandatory driver's licenses for operators of motor vehicles.

October

 * October – Frank Nelson Cole proves that 267-1 is composite by factoring it as 193,707,721 * 761,838,257,287 after trying every Sunday for 3 years.
 * October 1 – First modern World Series: The Boston Red Sox defeat the Pittsburgh Pirates.
 * October 6 – The High Court of Australia sits for the first time.
 * October 10 – The Women's Social and Political Union is founded in the UK.

November

 * November 3 – With the encouragement of the United States, Panama proclaims itself independent from Colombia.
 * November 13 – The United States recognizes the independence of Panama.
 * November 17 – The Russian Social Democratic Labour Party splits into two groups; the Bolsheviks (Russian for "majority") and Mensheviks (Russian for "minority").
 * November 18 – The Hay–Bunau-Varilla Treaty is signed by the United States and Panama, giving the U.S. exclusive rights over the Panama Canal Zone.
 * November 23 – Colorado Governor James Hamilton Peabody sends the state militia into the town of Cripple Creek to break up a miners' strike.

December

 * December 16 – The Taj Mahal Palace Hotel in Bombay opens its doors to guests.
 * December 17 – Orville Wright flies an aircraft with a petrol engine at Kitty Hawk, North Carolina in the first documented, successful, controlled, powered, heavier-than-air flight.
 * December 30 – Iroquois Theatre fire in Chicago kills 600.

Date unknown

 * The Lincoln–Lee Legion is established to promote the American temperance movement and signing of alcohol abstinence pledges by children.
 * The first box of Crayola crayons is made and sold for 5 cents. It contains 8 colors; brown, red, orange, yellow, green, blue, violet and black.
 * Osea Island off Maldon, Essex, England, is bought by Frederick Nicholas Charrington to provide an addiction treatment centre.
 * Royal Enfield starts making Motor Cycles.
 * Texas State University in San Marcos, TX opens its doors as Southwest Texas Normal School.

January

 * January 6 – Maurice Abravanel, Greek-born conductor (d. 1993)
 * January 10 – Barbara Hepworth, English sculptor (d. 1975)
 * January 11 – Alan Paton, South African author and anti-apartheid, activist. (d. 1988)
 * January 12 – Igor Kurchatov, Soviet physicist (d. 1960)
 * January 16
 * Peter Brocco. American actor (d. 1992)
 * William Grover-Williams, French race car driver and war hero (d. 1945)
 * January 17 – Warren Hull, American actor (d. 1974)
 * January 22 – Fritz Houtermans, Polish physicist (d. 1966)
 * January 23 – Jorge Eliécer Gaitán, Colombian politician (d. 1948)
 * January 27 – John Eccles, Australian neuropsychologist, recipient of the Nobel Prize in Physiology or Medicine (d. 1997)

February

 * February 2 – Bartel Leendert van der Waerden, Dutch mathematician (d. 1996)
 * February 3 – Douglas Douglas-Hamilton, 14th Duke of Hamilton, Scottish nobleman and pioneering aviator (d. 1973)
 * February 4 – Alexander Imich, American parapsychologist and chemist (d. 2014)
 * February 6 – Claudio Arrau, Chilean-born pianist (d. 1991)
 * February 8
 * Greta Keller, Vienna-born cabaret singer and actress (d. 1977)
 * Tunku Abdul Rahman, first Prime Minister of Malaysia (d. 1990)
 * February 10
 * Waldemar Hoven, German physician (d. 1948)
 * Matthias Sindelar, Austrian footballer (d. 1939)
 * February 11
 * Rex Lease, American actor (d. 1966)
 * Hans Redlich, Austrian composer (d. 1968)
 * February 13 – Georges Simenon, French writer (d. 1989)
 * February 14 – Stuart Erwin, American actor (d. 1967)
 * February 16 – Edgar Bergen, American ventriloquist (d. 1978)
 * February 21
 * Anaïs Nin, French writer (d. 1977)
 * Raymond Queneau, French poet and novelist (d. 1976)
 * February 22
 * Morley Callaghan, Canadian writer and media personality (d. 1990)
 * Ain-Ervin Mere, Estonian Nazi (d. 1969)
 * Frank P. Ramsey, English mathematician (d. 1930)
 * February 24 – Vladimir Bartol, Slove author (d. 1967)
 * February 26 – Giulio Natta, Italian chemist, Nobel Prize laureate (d. 1979)
 * February 27 – Grethe Weiser, German actress (d. 1970)
 * February 28 – Vincente Minnelli, American director (d. 1986)

March

 * March 4
 * Luis Carrero Blanco, Spanish statesman (d. 1973)
 * William C. Boyd, American immunochemist (d. 1983)
 * Dorothy Mackaill, British-born American actress (d. 1990)
 * John Scarne, American magician and card expert (d. 1985)
 * March 6 – Empress Kōjun, Empress consort of Japan (d. 2000)
 * March 10
 * Bix Beiderbecke, American jazz musician (d. 1931)
 * Clare Boothe Luce, American publisher and writer (d. 1987)
 * March 11
 * Ronald Syme, New Zealand-born classicist and historian (d. 1989)
 * Lawrence Welk, American television musician (d. 1992)
 * March 14 – Mustafa Barzani, Kurdish politician (d. 1979)
 * March 18 – Gian Galeazzo Ciano, 2nd Count of Cortellazzo and Buccari, Italian aristocrat and diplomat (d. 1944)
 * March 20 – Edgar Buchanan, American actor (d. 1979)
 * March 21 – Frank Sargeson, New Zealand writer (d. 1982)
 * March 24
 * Adolf Butenandt, German chemist, Nobel Prize laureate (d. 1995)
 * Malcolm Muggeridge, English journalist (d. 1990)
 * March 25 – Nahum Norbert Glatzer, Jewish-American scholar (d. 1990)
 * March 27 – Betty Balfour, English screen actress (d. 1977)
 * March 28 – Rudolf Serkin, Austrian pianist (d. 1991)
 * March 31 – H. J. Blackham, British humanist and author (d. 2009)

April

 * April 5 – Hilda Bruce, British zoologist (d. 1974)
 * April 6
 * Mickey Cochrane, American baseball player (d. 1962)
 * Doc Edgerton, American electrical engineering (d. 1990)
 * April 12 – Jan Tinbergen, Dutch economist, Nobel Prize laureate (d. 1994)
 * April 9 – Gregory Goodwin Pincus, American biologist and researcher (d. 1967)
 * April 15 – John Williams, English-born actor (d. 1983)
 * April 17
 * Gregor Piatigorsky, Russian cellist (d. 1976)
 * Morgan Taylor, American athlete (d. 1975)
 * April 19 – Eliot Ness, American treasury agent (d. 1957)
 * April 24 – José Antonio Primo de Rivera, Spanish politician (d. 1936)
 * April 25 – Andrey Kolmogorov, Russian mathematician (d. 1987)

May

 * May 2 – Benjamin Spock, American pediatrician (d. 1998)
 * May 3 – Bing Crosby, American singer and actor (d. 1977)
 * May 4 – Luther Adler, American actor (d. 1984)
 * May 6 – Toots Shor, New York restaurateur (d. 1977)
 * May 8 – Fernandel, French actor (d. 1971)
 * May 10 – Hans Jonas, German-born philosopher(d. 1993)
 * May 11 – Charlie Gehringer, baseball player (d. 1993)
 * May 18 – Frits Warmolt Went, Dutch botanist (d. 1990)
 * May 24 – Lofton R. Henderson, American naval aviator, died in the Battle of Midway (d. 1942)
 * May 25 – Binnie Barnes, English actress (d. 1988)
 * May 29 – Bob Hope, English-born American comedian and actor (d. 2003)

June

 * June 1 – Vasyl Velychkovsky Ukrainian bishop (d. 1973)
 * June 6 – Aram Khachaturian, Armenian composer (d. 1978)
 * June 6 – Bakht Singh, Indian evangelist, well-known bible teacher and preacher (d. 2000)
 * June 8 – Marguerite Yourcenar, Belgian-French author (d. 1987)
 * June 10 – Theo Lingen, German actor (d. 1978)
 * June 12 – Emmett Hardy, American musician (d. 1925)
 * June 15 – Huldreich Georg Früh, Swiss composer (d. 1945)
 * June 18
 * Jeanette MacDonald, American singer and actress (d. 1965)
 * Raymond Radiguet, French author (d. 1923)
 * June 19
 * Lou Gehrig, American baseball player (d. 1941)
 * Wally Hammond, English cricketer (d. 1965)
 * June 20 – Eddie Laughton, British-born American film actor (d. 1952)
 * June 21 – Al Hirschfeld, American caricaturist (d. 2003)
 * June 22
 * John Dillinger, American bank robber (d. 1934)
 * Jiro Horikoshi, Japanese aircraft designer (d. 1982)
 * Ben Pollack, American jazz drummer and bandleader (d. 1971)
 * Ben Robertson, American novelist, journalist, and war correspondent (d. 1943)
 * June 23 – Frances Dewey Wormser, American stage actress, entertainer and vaudeville performer (d. 2008)
 * June 25
 * Pierre Brossolette, French journalist and resistance fighter (d. 1944)
 * George Orwell, English author (d. 1950)
 * June 29 – Alan Blumlein, British electronics engineer (d. 1942)

July

 * July 1 – Amy Johnson, English aviator (d. 1941)
 * July 2
 * Harwell Hamilton Harris, American architect (d. 1990)
 * Alec Douglas-Home, Prime Minister of the United Kingdom (d. 1995)
 * King Olav V of Norway (d. 1991)
 * July 3 – Ace Bailey, Canadian hockey player (d. 1992)
 * July 4 – Corrado Bafile, Italian Catholic cardinal (d. 2005)
 * July 6 – Hugo Theorell, Swedish scientist, recipient of the Nobel Prize in Physiology or Medicine (d. 1982)
 * July 10 – John Wyndham, British author (d. 1969)
 * July 13 – Kenneth Clark, English art historian (d. 1983)
 * July 21 – Roy Neuberger, American financier and art collector (d. 2010)
 * July 27 – Michail Stasinopoulos, 1st President of Greece (d. 2002)

August

 * August 3
 * Habib Bourguiba, former President of Tunisia (d. 2000)
 * Fahri Korutürk, former President of Turkey (d. 1987)
 * August 6 – Virginia Foster Durr, American civil rights activist (d. 1999)
 * August 7
 * Rudolph Ising, cartoon animator (d. 1992)
 * Louis Leakey, British archaeologist (d. 1972)
 * August 13 – Chubby Johnson, American actor (d. 1974)
 * August 14 –Lodewijk Bruckman, Dutch painter (d. 1995)
 * August 19 – James Gould Cozzens, American writer (d. 1978)
 * August 24 –Graham Sutherland, English artist (d. 1980)
 * August 26 – Ian Dalrymple, British screenwriter, film director and producer (d. 1989)
 * August 31
 * Arthur Godfrey, American radio and television host (d. 1983)
 * Hugh Harman, cartoon animator (d. 1982)

September

 * September 7
 * Dorothy Marie Donnelly, American poet (d. 1994)
 * Shimaki Kensaku, Japanese author (d. 1945)
 * John Kloza, Polish professional baseball player and manager (d. 1962)
 * September 8 – Jane Arbor, British writer (d. 1994)
 * September 9
 * Lev Shankovsky, Ukrainian military historian (d. 1995)
 * Edward Upward, English author (d. 2009)
 * Phyllis Whitney, American mystery writer (d. 2008)
 * September 10 – Cyril Connolly, English critic and writer (d. 1974)
 * September 11 – Theodor Adorno, German philosopher (d. 1969)
 * September 13 – Claudette Colbert, American actress (d. 1996)
 * September 15 – Roy Acuff, American country musician (d. 1992)
 * September 17 – Karel Miljon, Dutch boxer (d. 1984)
 * September 21 – Preston Tucker, American automobile designer (d. 1956)
 * September 22 – Joseph Valachi, American gangster (d. 1971)
 * September 25
 * Abul A'la Maududi, Pakistani journalist, theologian, and philosopher (d. 1979)
 * Mark Rothko, Latvian-born painter (d. 1970)
 * September 30 – Lyle Goodhue, American chemist, inventor and entomologist (d. 1981)

October

 * October 1 – Vladimir Horowitz, Russian pianist (d. 1989)
 * October 4 – John Vincent Atanasoff, American computer engineer (d. 1995)
 * October 5 – M. King Hubbert, American geophysicist (d. 1989)
 * October 6 – Ernest Walton, Irish physicist, Nobel Prize laureate (d. 1995)
 * October 9 – Walter O'Malley, American baseball executive (d. 1979)
 * October 10 – Bei Shizhang, Chinese biologist and educator (d. 2009)
 * October 16 – Cecile de Brunhoff, French storyteller (d. 2003)
 * October 18 – Lina Radke, German athlete (d. 1983)
 * October 22
 * George Wells Beadle, American geneticist, recipient of the Nobel Prize in Physiology or Medicine (d. 1989)
 * Zlatyu Boyadzhiev, Bulgarian painter (d. 1976)
 * Jerome "Curly Howard" Horwitz, American comedian and actor (The Three Stooges) (d. 1952)
 * October 23 – Thaddeus B. Hurd, American architect and historian (d. 1989)
 * October 25
 * Katharine Byron, American politician (d. 1976)
 * Harry Shoulberg, American painter (d. 1995)
 * October 26 – Bill Allington, American baseball player and manager (d. 1966)
 * October 28 – Evelyn Waugh, English writer (d. 1966)
 * October 29 – Vivian Ellis, English composer and lyricist (d. 1996)

November

 * November 1 – Max Adrian, Northern Irish actor (d. 1973)
 * November 2 – Edgard Potier, Belgian spy (d. 1944)
 * November 3 – Walker Evans, American photographer (d. 1975)
 * November 4 – Watchman Nee, Chinese preacher and church leader (d. 1972)
 * November 6 – Carl Rakosi, German-born poet (d. 2004)
 * November 7 – Konrad Lorenz, Austrian zoologist, recipient of the Nobel Prize in Physiology or Medicine (d. 1989)
 * November 8 – Alfred Thambiayah, Ceylon Tamil businessman and politician
 * November 11 – Blessed Victoria Díez Bustos de Molina, Spanish teacher and religious woman (d. 1936)
 * November 19 – Nancy Carroll, American actress (d. 1965)
 * November 27 – Lars Onsager, Norwegian chemist, Nobel Prize laureate (d. 1976)
 * November 29 – E. Harold Munn, American temperance movement leader and presidential candidate (d. 1992)

December

 * December 4
 * Lazar Lagin, Soviet writer (d. 1979)
 * A. L. Rowse, English historian (d. 1997)
 * December 5
 * Johannes Heesters, Dutch singer and actor (d. 2011)
 * Cecil Frank Powell, British physicist, Nobel Prize laureate (d. 1969)
 * December 12
 * Dagmar Nordstrom, American composer and pianist (d. 1976)
 * Yasujirō Ozu, Japanese film director (d. 1963)
 * December 13 – Ella Baker, American civil rights activist (d. 1986)
 * December 17 – Erskine Caldwell, American author (d. 1987)
 * December 19 – George Davis Snell, American geneticist, recipient of the Nobel Prize in Physiology or Medicine (d. 1996)
 * December 22 – Haldan Keffer Hartline, American physiologist, Nobel Prize laureate (d. 1983)
 * December 24 – Joseph Cornell, American sculptor (d. 1972)
 * December 26 – Elisha Cook Jr., American actor (d. 1995)
 * December 28
 * Earl Hines, American jazz pianist (d. 1983)
 * John von Neumann, Hungarian-born mathematician (d. 1957)
 * December 31 – Nathan Milstein, Ukrainian violinist (d. 1992)

January–June

 * January 3 – Alois Hitler, Austrian civil servant, father of Adolf Hitler (b. 1837)
 * January 4 – Alexandr Aksakov, Russian writer (b. 1832)
 * January 5 – Práxedes Mateo Sagasta, Spanish politician, former Prime Minister (b. 1825)
 * January 17 – Quintin Hogg, British philanthropist (b. 1845)
 * January 28
 * Augusta Holmès, French composer (b. 1847)
 * Robert Planquette, French composer (b. 1850)
 * February 1 – Sir George Gabriel Stokes, Irish mathematician and physicist (b. 1819)
 * February 7 – James Glaisher, English meteorologist and aeronaut (b. 1809)
 * February 14 – Archduchess Elisabeth Franziska of Austria (b. 1831)
 * February 22 – Hugo Wolf, Austrian composer (b. 1860)
 * February 26 – Richard Jordan Gatling, American inventor (b. 1818)
 * March 4 – Joseph Henry Shorthouse, English novelist (b. 1834)
 * March 5 – Gaston Paris, French scholar (b. 1839)
 * March 13 – George Granville Bradley, English vicar and scholar (b. 1821)
 * March 16 – Roy Bean, American pioneer (b. 1825)
 * March 28 – Émile Baudot, French telegraph engineer (b. 1845)
 * April 4 – Margaret Ann Neve, supercentenarian (b. 1792)
 * April 11 – Gemma Galgani, Italian mystic and Catholic saint (b. 1878)
 * April 13 – Moritz Lazarus, German philosopher (b. 1824)
 * April 19 – Oliver Mowat, Canadian politician (b. 1820)
 * April 28 – Josiah Willard Gibbs, American physical chemist (b. 1839)
 * April 29 – Stuart Robson, American stage actor and comedian (b. 1836)
 * May 4 – Gotse Delchev, Bulgarian revolutionary (b. 1872)
 * May 8 – Paul Gauguin, French painter (b. 1848)
 * May 13 – Apolinario Mabini, Filipino political theoretician and Prime Minister (b.1864)
 * June 9 – Gaspar Núñez de Arce, Spanish poet (b. 1834)
 * June 11
 * Nikolai Bugaev, Russian mathematician (b. 1837)
 * Draga Mašin, Serbian queen consort (b. 1861)
 * Alexander I, King of Serbia (b. 1876)
 * June 19 – Herbert Vaughan, English Catholic cardinal and archbishop (b. 1832)

July–December

 * July 2 – Ed Delahanty, American baseball player and MLB Hall of Famer (b. 1867)
 * July 11 – William Ernest Henley, English poet, critic, and editor (b. 1849)
 * July 13 – Béni Kállay, Austro-Hungarian statesman (b. 1839)
 * July 17 – James McNeill Whistler, American painter (b. 1834)
 * July 20 – Pope Leo XIII, Italian Roman Catholic Pope (b. 1810)
 * August 1 – Calamity Jane, American frontierswoman (b. 1852)
 * August 5 – Phil May, English artist (b. 1864)
 * August 8 – Adolf Schiel, German-born officer in Boer armed forces (b. 1858)
 * August 11 – Eugenio María de Hostos, Puerto Rican philosopher and sociologist (b. 1839)
 * August 17 – Hans Gude, Norwegian painter (b. 1825)
 * August 22 – Lord Salisbury, Prime Minister of the United Kingdom (b. 1830)
 * August 23 – Fray Mocho, Argentine writer (b. 1858)
 * September 13 – Carl Schuch, Austrian painter (b. 1846)
 * September 18 – Alexander Bain, Scottish philosopher (b. 1818)
 * October 4 – Otto Weininger, Austrian-Jewish author (b. 1880)
 * October 20 – Thomas Vincent Welch, American politician (b. 1850)
 * October 22 – William Edward Hartpole Lecky, Irish historian and member of the House of Commons (b. 1838)
 * November 1 – Theodor Mommsen, German writer, Nobel Prize laureate (b. 1817)
 * November 13 – Camille Pissarro, French painter (b. 1830)
 * November 25 – Sabino Arana, Spanish Basque writer and nationalist (b. 1865)
 * December 8 – Herbert Spencer, English philosopher (b. 1820)

Nobel Prizes

 * Physics – Antoine Henri Becquerel, Pierre Curie, and Marie Curie
 * Chemistry – Svante August Arrhenius
 * Medicine – Niels Ryberg Finsen
 * Literature – Bjørnstjerne Bjørnson
 * Peace – William Randal Cremer