1905 (MCMV) was a common year starting on Sunday (dominical letter A) of the Gregorian calendar and a common year starting on Saturday (dominical letter B) of the Julian calendar, the 1905th year of the Common Era (CE) and Anno Domini (AD) designations, the 905th year of the 2nd millennium, the fifth year of the 20th century, and the sixth year of the 1900s decade. As of the start of 1905, the Gregorian calendar was 13 days ahead of the Julian calendar, which remained in localised use until 1918.
As the second year of the massive Russo-Japanese War began, more than 100,000 died in the largest world battles of that era, and the war chaos lead to a revolution against the Tsar. (Shostakovich's 11th Symphony is subtitled "The Year 1905" to commemorate this.) Canada and the U.S. expanded west, with the Alberta and Saskatchewan provinces and the founding of Las Vegas. 1905 is additionally the annus mirabilis of Albert Einstein, who published papers which lay the foundations for quantum physics, introduced the special theory of relativity, explained Brownian motion, and established mass–energy equivalence.
- January 1 – The Trans-Siberian Railway officially opens after its completion on July 21, 1904.
- January 2 – Russo-Japanese War: The Russian Army surrenders at Port Arthur in Qing dynasty China.
- January 5 – The play The Scarlet Pimpernel opens at the New Theatre in London and begins a run of 122 performances and numerous revivals.
- January 22 (January 9 O.S.) – The Bloody Sunday massacre of peaceful Russian demonstrators led by Russian Orthodox priest Father Gapon at the Winter Palace in Saint Petersburg helps trigger the abortive Revolution of 1905.
- January 26
- February 12 – In Christchurch, New Zealand, the Cathedral of the Blessed Sacrament is opened.
- February 16 – At Haulbowline Base in Ireland, two explosions on board HM Submarine A5, due to petrol fumes after refueling, kill six of the eleven crew.
- February 17 – At Fremantle, the R.M.S. Orizaba is wrecked, but all 160 passengers and the mail are saved.
- February 20 – Russo-Japanese War: The Battle of Mukden begins in Manchuria.
- February 23 – Rotary International is founded.
- March 1 – Australian Conservative leader Richard Butler takes office as Premier of South Australia.
- March 3 – Tsar Nicholas II of Russia agrees to create an elected assembly (the Duma).
- March 4 – United States President Theodore Roosevelt begins a full term.
- March 5 – Russo-Japanese War: Russian troops begin to retreat from Mukden after losing 100,000 troops in 3 days.
- March 10
- March 13 – Mata Hari introduces her exotic dance act in Paris.
- March 17 – Albert Einstein publishes his paper "On a heuristic viewpoint concerning the production and transformation of light", in which he explains the photoelectric effect using the notion of light quanta.
- March 20 – Grover Shoe Factory disaster: A boiler explosion, building collapse and fire in Brockton, Massachusetts kills 58.
- March 23 – Theriso revolt breaks out on Crete when about 1,500 men led by Eleftherios Venizelos meet at the village of Theriso to challenge the island's authoritarian government and press for its unification with Greece.
- March 31 – Wilhelm II, German Emperor asserts German equality with France in Morocco, triggering the Tangier or First Moroccan Crisis.
- April – Albert Einstein works on the special theory of relativity as well as the theory of Brownian motion.
- April 1 – Penny Post established between the United Kingdom and Australia.
- April 2 – The Simplon Tunnel is officially opened through the Alps.
- April 4 – In India, the 1905 Kangra earthquake hits the Kangra Valley, kills 20,000, and destroys most buildings in Kangra, McLeod Ganj and Dharamsala.
- April 6 – Lochner v. New York: The Supreme Court of the United States invalidates New York's 8-hour-day law.
- April 14 – Erik Gustaf Boström resigns as the Prime Minister of Sweden, over the issue of the Swedish-Norwegian Union. His Minister without Portfolio, Johan Ramstedt, becomes the new Prime Minister of Sweden.
- May 11 – Albert Einstein submits his doctoral dissertation "On the Motion of Small Particles...", in which he explains Brownian motion. In the course of the year, Einstein publishes four papers, formulates the theory of special relativity and explains the photoelectric effect by quantization. 1905 is regarded as his "miracle year".
- May 15 – Las Vegas is founded when 110 acres (0.45 km2), in what later becomes downtown, are auctioned off.
- May 17 – Kappa Delta Rho is founded in room 14 of Old Painter Hall at Middlebury College in Middlebury, Vermont.
- May 27–May 28 – Russo-Japanese War – Battle of Tsushima: The Japanese fleet under Admiral Heihachiro Togo destroys the Russian fleet under Admiral Zinovi Petrovich Rozhdestvenski in a 2-day battle.
- June 7 – The Norwegian Parliament declares the union with Sweden dissolved, and Norway achieves full independence.
- June 9 – The Charlton Athletic F.C. is founded.
- June 15 – Princess Margaret of Connaught marries Prince Gustaf Adolf of Sweden, Duke of Skåne (Gustaf VI Adolf of Sweden).
- June 27 – (June 14 in the Julian calendar): Mutiny breaks out on the Russian ironclad Potemkin.
- June 29 – The Automobile Association is founded in the United Kingdom.
- June 30 – Albert Einstein publishes the article "On the Electrodynamics of Moving Bodies" where he reveals his theory of special relativity.
- July 22 – Taft–Katsura Secret Agreement.
- July 23 – Alfred Deakin becomes Prime Minister of Australia for the second time.
- August 2 – The businessman and right-wing politician Christian Lundeberg becomes Prime Minister of Sweden.
- August 12 – Leopold II of Belgium opens the Antwerpen-Centraal railway station.
- August 12 – First running of the Shelsley Walsh Speed Hill Climb, the world's oldest motorsport event to have been staged continuously on its original course
- August 25 – The Ancient Order of Druids initiate neo-Druidic rituals at Stonehenge in England.
- August – Pablo Valencia gets lost in the Sonoran Desert with no water.
- September 1 – The Canadian provinces of Alberta and Saskatchewan are established from the southwestern part of the Northwest Territories.
- September 5 – Russo-Japanese War – Treaty of Portsmouth: In New Hampshire, a treaty mediated by U.S. President Theodore Roosevelt is signed by victor Japan and Russia. Russia cedes the island of Sakhalin and port and rail rights in Manchuria to Japan.
- September 8 – The 7.2 Mw Calabria earthquake shakes Southern Italy with a maximum Mercalli intensity of XI (Extreme), killing between 557 and 2,500 people.
- September 27 – Albert Einstein submits his paper "Does the Inertia of a Body Depend Upon Its Energy Content?" in which he develops an argument for the famous equation E = mc2.
- October – Fauvist artists, led by Henri Matisse and André Derain, first exhibit, at the Salon d'Automne in Paris.
- October 2 – HMS Dreadnought is laid down in the United Kingdom, revolutionising battleship design and triggering a naval arms race.
- October 5 – The Wright brothers' third aeroplane (Wright Flyer III) stays in the air for 39 minutes with Wilbur piloting, the first aeroplane flight lasting over half an hour.
- October 16 – The Partition of Bengal is made by Lord Curzon to separate the region of Bengal by Muslim and Hindu territories, until its reunification in 1911.
- October 20 – Galatasaray S.K. sports and Association football club is founded in Istanbul.
- October 26 – Sweden agrees to the repeal of the union with Norway.
- October 29
- (October 16 Old Style) Russian Revolution of 1905: The Imperial Russian Army opens fire on a meeting at a street market in Tallinn, Governorate of Estonia, killing 94 and injuring over 200 people.
- (October 16 Old Style) The Circum-Baikal Railway is brought into permanent operation, completing through rail communication on the Trans-Siberian Railway.
- October 30 (October 17 Old Style) – October Manifesto: Tsar Nicholas II of Russia is forced to announce the granting of his country's first constitution (the Russian Constitution of 1906), conceding a national assembly (State Duma) with limited powers.
- November 4 – The application of the infamous February Manifesto, removing the veto of the Diet of the autonomous Grand Principality of Finland over matters considered by the Emperor to concern Russian imperial interests, is interrupted by the new November Manifesto. The Senate of Finland is ordered to put forward a proposal for parliamentary reform based on unicameralism and universal and equal suffrage.
- November 7 – The solicitor and liberal politician Karl Staaff becomes Prime Minister of Sweden, after an Riksdag election based mainly on voting rights reform.
- November 9 – The Province of Alberta, Canada, holds its first general election.
- November 17 – Japan–Korea Treaty of 1905 ("Eulsa Treaty") effectively makes Korea a protectorate of Japan.
- November 18 – Prince Carl of Denmark becomes King Haakon VII of Norway.
- November 27 – Moravian Copromise.
- November 28 – Irish nationalist Arthur Griffith founds Sinn Féin in Dublin as a political party whose goal is independence for all of Ireland.
- November-December – Russian Revolution of 1905: In the Baltic governorates, workers and peasants burn and loot hundreds of Baltic German manors. The punitive Imperial Russian Army thereafter executes and deports thousands of looters.
- December 7–18 – Moscow Uprising, led mainly by Bolsheviks and suppressed by the army.
- December 9 – 1905 French law on the Separation of the Churches and the State is passed, enacting laïcité.
- December 11 – In support of the Moscow Uprising, the Council of Workers' Deputies of Kiev stages a mass uprising, establishing the Shuliavka Republic in the city, December 12–16.
- December 30
- Non-aboriginal women are given the vote and admitted to the practise of law in Queensland.
- Workers' compensation is introduced in Queensland.
- The title Prime Minister of the United Kingdom is officially recognised by Edward VII.
- Pathé Frères colours black and white films by machine.
- Huckleberry Finn and Tom Sawyer are banned from the Brooklyn Public Library for setting a "bad example."
- Alfred Einhorn introduces novocaine.
- Wolves become extinct in Japan.
- Civil service examinations are abolished in Qing dynasty China.
- Germany insists on an international conference on the Moroccan question.
- Max Weber publishes Die Protestantische Ethik und der Geist des Kapitalismus.
- January 1 – Malek Bennabi, Algerian philosopher (d. 1973)
- January 2 – Michael Tippett, English composer (d. 1998)
- January 3
- January 4 – Sterling Holloway, American actor (d. 1992)
- January 8 – Giacinto Scelsi, Italian composer (d. 1988)
- January 12
- January 13 – Kay Francis, American actress (d. 1968)
- January 14 – Takeo Fukuda, 67th Prime Minister of Japan from 1976-1978 (d.1995)
- January 17 – Guillermo Stábile, Argentine football player and manager (d. 1966)
- January 18 – Joseph Bonanno, American gangster (d. 2002)
- January 19 – Stanley Hawes, British-born Australian film producer, director and administrator (d. 1991)
- January 21 – Christian Dior, French couturier (d. 1957)
- January 24 – J. Howard Marshall, American billionaire (d. 1995)
- January 26
- January 27 – Howard McNear, American actor (d. 1969)
- January 29 – Barnett Newman, American painter (d. 1970)
- January 31 – John O'Hara, American writer (d. 1970)
- February 1 – Emilio G. Segrè, Italian physicist, Nobel Prize laureate (d. 1989)
- February 2 – Ayn Rand, American author (The Fountainhead) (d. 1982)
- February 4 – Hylda Baker, English actress (d. 1986)
- February 7 – Paul Nizan, French author (d. 1940)
- February 10
- February 15 – Harold Arlen, American composer of popular music (d. 1986)
- February 18 – Queenie Leonard, British character actress and singer (d. 2002)
- February 23 – Derrick Henry Lehmer, American mathematician (d. 1991)
- February 26 – Arthur Brough, English actor (d. 1978)
- February 27 – Franchot Tone, American actor (d. 1968)
- March 1 – Doris Hare, English actress (d. 2000)
- March 2 – Geoffrey Grigson, British poet, writer, critic (d. 1985)
- March 3 – Marie Glory, French silent-screen actress (d. 2009)
- March 6 – Bob Wills, American singer (d. 1975)
- March 9 – Gerard Helders, Dutch politician (d. 2013)
- March 10 – Richard Haydn, English comic actor (d. 1985)
- March 12 – Takashi Shimura, Japanese actor (d. 1982)
- March 15 – Berthold Schenk Graf von Stauffenberg, German solicitor and Nazi opponent (d. 1944)
- March 16 – Elisabeth Flickenschildt, German actress (d. 1977)
- March 18
- March 19
- March 20
- March 23
- March 24 – Pura Santillan-Castrence, Filipino writer and diplomat (d. 2007)
- March 27 – Elsie MacGill, Canadian aeronautical engineer (d. 1980)
- March 28 – Marlin Perkins, American zoologist and television host, Mutual of Omaha's Wild Kingdom (d. 1986)
- March 30
- April 19 – John Thach, American naval aviator and admiral (d. 1981)
- April 21 – Edmund G. Brown, Governor of California (d. 1996)
- April 25 – George Nepia, New Zealand Maori rugby player (d. 1986)
- April 26 – Raúl Leoni, President of Venezuela, (d. 1972)
- April 30 – Sergey Nikolsky, Russian mathematician (d. 2012)
- May 3 – Werner Fenchel, German mathematician (d. 1988)
- May 5 – Floyd Gottfredson, American "Mickey Mouse" comic strip cartoonist (d. 1986)
- May 8 – Red Nichols, American jazz musician (d. 1965)
- May 13 – Fakhruddin Ali Ahmed, Indian solicitor and politician, fifth President of India (d. 1977)
- May 14
- May 15 – Joseph Cotten, American actor (d. 1994)
- May 16 – Henry Fonda, American actor (The Grapes of Wrath) (d. 1982)
- May 17 – Roy Nelson, American cartoonist (d. 1956)
- May 20 – Gerrit Achterberg, Dutch poet (d. 1962)
- May 27 – Signe Johansson-Engdahl, Swedish Olympic diver (d. 2010)
- May 28 – Sada Abe, Japanese actress (d. 1970)
- May 29 – Sebastian Shaw, English actor (d. 1994)
- June 1 – Robert Newton, English stage and film actor (d. 1956)
- June 7 – James J. Braddock, Irish-American wrestler (d. 1974)
- June 12 – Ray Barbuti, American athlete (d. 1975)
- June 14 – Arthur Davis, American animator (d. 2000)
- June 19 – Mildred Natwick, American stage and film actress (d. 1994)
- June 21 – Jean-Paul Sartre, French existentialist (d. 1980)
- June 23 – Mary Livingstone, American radio comedian (d. 1983)
- June 30 – Nestor Paiva, American actor (d. 1966)
- July 4 – Irving Johnson, American sail training pioneer (d. 1991)
- July 5 – Jock Cameron, South African cricketer (d. 1935)
- July 8 – Leonid Amalrik, Russian animator (d. 1997)
- July 12
- July 13 – Alfredo M. Santos, Filipino general (d. 1990)
- July 15 – Dorothy Fields, American songwriter (d. 1988)
- July 22 – Doc Cramer, American baseball player (d. 1990)
- July 23 – Leopold Engleitner, Austrian Holocaust survivor (d. 2013)
- July 25 – Elias Canetti, Bulgarian-born British writer (d. 1994)
- July 29
- July 30 – Pedro Quartucci, Argentine boxer and actor (d. 1983)
- August 2 – Karl Amadeus Hartmann, German composer (d. 1963)
- August 2
- August 3
- August 8 – André Jolivet, French composer (d. 1974)
- August 9 – Leo Genn, English actor (d. 1978)
- August 11 – Erwin Chargaff, Austrian biochemist (d. 2002)
- August 16 – Marian Rejewski, Polish mathematician and cryptologist (d. 1980)
- August 18 – Amelia Boynton Robinson, American civil rights activist (d. 2015)
- August 20
- August 22 – John Lyng, Norwegian politician, former prime minister (d. 1978)
- August 23 – Constant Lambert, British composer (d. 1951)
- August 24 – Siaka Stevens, former President of Sierra Leone (d. 1988)
- August 25 – Faustina Kowalska, Polish saint, the Secretary of Divine Mercy (d. 1938)
- August 29
- August 31 – Dore Schary, American film writer, director, and producer (d. 1980)
- September 1 – Elvera Sanchez, Puerto Rican dancer (d. 2000)
- September 3 – Carl David Anderson, American physicist, Nobel Prize laureate (d. 1991)
- September 5 – Justiniano Montano, Filipino politician (d. 2005)
- September 18
- September 22
- September 24 – Severo Ochoa, Spanish–American biochemist, Nobel Prize laureate (d. 1993)
- September 26 – Emilio Navarro, Puerto Rican baseball player (d. 2011)
- September 28 – Max Schmeling, German boxer (d. 2005)
- September 30
- October 6 – Helen Wills Moody, American tennis player (d. 1998)
- October 7 – Andy Devine, American character actor (d. 1977)
- October 11 – Fred Trump, American real estate developer (d. 1999)
- October 18 – Félix Houphouët-Boigny, former President of Côte d'Ivoire (d. 1993)
- October 23
- October 29 – Berthold Wolpe, German-born British calligrapher, typographer and illustrator (d. 1989)
- October 31 – Harry Frederick Harlow, American psychologist (d. 1981)
- November 1 – Eric Siday, American bandleader and electronic composer (d. 1976)
- November 2
- November 4 – Dragutin Tadijanović, Croatian poet (d. 2007)
- November 5 – Sajjad Zaheer, Urdu writer and revolutionary (d. 1973)
- November 7 – William Alwyn, English composer (d. 1985)
- November 9 – Erika Mann, German author and war correspondent (d. 1969)
- November 15 – Mantovani, Italian-born conductor and arranger (d. 1980)
- November 17 – Queen Astrid of Belgium (d. 1935)
- November 19 – Eleanor Audley, American actress (d. 1991)
- November 26 – Bob Johnson, American baseball player (d. 1982)
- December 5
- December 7
- December 8 – Frank Faylen, American movie and television actor (d. 1985)
- December 11 – Gilbert Roland, Mexican-born American actor (d. 1994)
- December 17 – Simo Häyhä, Finnish sniper (d. 2002)
- December 19 – Irving Kahn, American financial analyst and investor (d. 2015)
- December 21 – Anthony Powell, British author (d. 2000)
- December 22 – Kenneth Rexroth, American poet (d. 1982)
- December 23 – Paul Caraway, American general and High Commissioner (d. 1985)
- December 24 – Howard Hughes, American millionaire, aviation pioneer and film mogul (d. 1976)
- December 27 – Cliff Arquette, American comic (d. 1974)
- December 31 – Jule Styne, English-born composer (d. 1994)
- Reg Bunn, English comic book artist (d. 1971)
- Gershon Liebman, French rabbi (d. 1997)
- Lilo Milchsack, born Lisalotte Duden, German promoter of Anglo-German relations (d. 1992)
- January 6 – José María Gabriel y Galán, Spanish poet (b. 1870)
- January 14 – Ernst Abbe, German physicist (b. 1840)
- January 19 – Debendranath Tagore, Indian philosopher (b. 1817)
- January 27 – Watson Heston, American cartoonist (b. 1846)
- February 2 – Adolf Bastian, German anthropologist (b. 1826)
- February 4 – Louis-Ernest Barrias, French sculptor (b. 1841)
- February 5 – Andrijica Šimić, Croatian hajduk (b. 1833)
- February 9 – Adolph von Menzel, German painter (b. 1815)
- February 12 – Marcel Schwob, French writer (b. 1867)
- February 15 – Lew Wallace, American writer, author of Ben-Hur: A Tale of the Christ (b. 1827)
- February 17 – Grand Duke Sergei Alexandrovich of Russia, (b. 1857)
- February 20 – Jeremiah W. Farnham, American merchant captain (b. c. 1828)
- March 3 – Antonio Annetto Caruana, Maltese archaeologist and author (b. 1830)
- March 6 – John Henninger Reagan, American Confederate politician (b. 1818)
- March 15
- March 24 – Jules Verne, French science fiction author (Twenty Thousand Leagues Under the Sea) (b. 1828)
- March 25 – Maurice Barrymore, British actor (b. 1849)
- March 28 – Huang Zunxian, Chinese poet and writer (b. 1848)
- April 4 – Constantin Meunier, Belgian painter and sculptor (b. 1831)
- April 9 – Frederic Thesiger, second Baron Chelmsford, British general (b. 1827)
- April 18 – Juan Valera, Spanish writer (b. 1824)
- April 23 – Joseph Jefferson, American actor (b. 1829)
- May 13 – Sam S. Shubert, American theatre owner (b. 1878)
- May 26 – Alphonse James de Rothschild, French banker and philanthropist (b. 1827)
- May 29 – Francisco Silvela, Spanish politician, former Prime Minister (b. 1843)
- June 1 – Émile Delahaye, French automotive pioneer (b. 1843)
- June 3 – James Hudson Taylor, British missionary (b. 1832)
- June 4 – Jan Mikulicz-Radecki, Polish-Austrian surgeon (b. 1850)
- June 7 – Carl Kellner (mystic), German mystic (b. 1851)
- June 17 – Máximo Gómez, Cuban general (b. 1836)
- June 18
- June 22 – Francis Lubbock, Governor of Texas (b. 1815)
- June 27 – Grigory Vakulinchuk, Russian mutineer (b. 1877)
- July 1 – John Hay, American diplomat and private secretary to Abraham Lincoln (b. 1838)
- July 4 – Élisée Reclus, French geographer (b. 1830)
- July 8 – Walter Kittredge, American musician and composer (b. 1834)
- July 11 – Muhammad Abduh, Egyptian philosopher and jurist (b. 1849)
- August 1 – John Brown, Canadian politician (b. 1841)
- August 4 – Walther Flemming, German biologist (b. 1843)
- August 14 – Simeon Solomon, British artist (b. 1840)
- August 31 – Francesco Tamagno, Italian opera singer (b. 1850)
- September 5 – Touch the Clouds, Minneconjou chief (b. c. 1838)
- September 13 – René Goblet, French politician, 52nd Prime Minister of France (b. 1828)
- September 14 – Pierre Savorgnan de Brazza, Franco-Italian explorer (b. 1852)
- September 18 – George MacDonald, Scottish author, poet and Christian minister (b. 1824)
- September 19 – Thomas John Barnardo, Irish philanthropist (b. 1845)
- October 3 – José-Maria de Heredia, French poet (b. 1842)
- October 6 – Ferdinand von Richthofen, German explorer and geographer (b. 1833)
- October 13 – Sir Henry Irving, English actor (b. 1838)
- October 15 – Mikhail Ivanovich Dragomirov, Russian general (b. 1830)
- October 29 – Étienne Desmarteau, Canadian athlete (b. 1873)
- November 2 – Albert von Kölliker, Swiss anatomist (b. 1817)
- November 17 – Adolphe, Grand Duke of Luxembourg (b. 1817)
- December 5 – Henry Eckford, British horticulturist (b. 1823)
- December 9 – Sir Richard Claverhouse Jebb, British scholar and politician (b. 1841)
- December 12 – Reimond Stijns, Belgian writer (b. 1850)