January 20 is the 20th day of the year in the Gregorian calendar. There are 345 days remaining until the end of the year (346 in leap years).
In astrology, it is the cusp day between Capricorn and Aquarius.
- 250 - Emperor Decius begins a widespread persecution of Christians in Rome. Pope Fabian was martyred. Afterwards the Donatist controversy over readmitting lapsed Christians disaffects many in North Africa.
- 1265 - In Westminster, the first English parliament conducts its first meeting in the Palace of Westminster, now also known as the "Houses of Parliament".
- 1320 - Duke Wladyslaw Lokietek becomes king of Poland.
- 1356 - Edward Balliol abdicates as King of Scotland.
- 1502 - The present-day location of Rio de Janeiro is first explored.
- 1523 - Christian II is forced to abdicate as King of Denmark and Norway.
- 1576 - The Mexican city of León is founded by order of the viceroy Don Martín Enríquez de Almansa.
- 1649 - Charles I of England goes on trial for treason and other "high crimes".
- 1667 - The Polish-Lithuanian Commonwealth cedes Kiev, Smolensk, and left-bank Ukraine to Imperial Russia in the treaty of Andrusovo.
- 1783 - The Kingdom of Great Britain signs a peace treaty with France and Spain, officially ending hostilities in the Revolutionary War.
- 1788 - The third and main part of First Fleet arrives at Botany Bay. Arthur Phillip decides Botany Bay is unsuitable for location of a penal colony, and decides to move to Port Jackson.
- 1801 - John Marshall is appointed the Chief Justice of the United States.
- 1839 - In the Battle of Yungay, Chile defeats a Peruvian and Bolivian alliance.
- 1840 - Dumont D'Urville discovers Adélie Land, Antarctica.
- 1840 - Willem II becomes King of the Netherlands.
- 1841 - Hong Kong Island is occupied by the British.
- 1885 - L.A. Thompson patents the roller coaster.
- 1887 - The United States Senate allows the Navy to lease Pearl Harbor as a naval base.
- 1892 - At the YMCA in Springfield, Massachusetts, the first official basketball game is played.
- 1920 - The American Civil Liberties Union is founded.
- 1921 - The first Constitution of Turkey is adopted, making fundamental changes in the source and exercise of sovereignty by consecrating the principle of national sovereignty.
- 1929 - In Old Arizona, the first full-length talking film filmed outdoors, is released.
- 1936 - Edward VIII becomes King of the United Kingdom.
- 1937 - Franklin Roosevelt is inaugurated for a second term as President of the United States. This is the first inauguration scheduled on January 20, following adoption of the 20th Amendment. Previous inaugurations were scheduled on March 4.
- 1942 - World War II: Nazis at the Wannsee conference in Berlin agree on the "final solution to the Jewish problem".
- 1944 - World War II: The Royal Air Force drops 2,300 tons of bombs on Berlin.
- 1945 - Hungary ends its involvement in the Second World War, agreeing to an armistice with the Allies.
- 1954 - The National Negro Network is established with 40 charter member radio stations.
- 1960 - Hendrik Verwoerd announces a plebiscite on whether South Africa should become a Republic.
- 1968 - The Houston Cougars defeat the UCLA Bruins 71-69 to win the Game of the Century.
- 1969 - The first pulsar is discovered, in the Crab Nebula.
- 1981 - Iran releases 52 American hostages twenty minutes after Ronald Reagan is inaugurated as U.S. President.
- 1986 - Martin Luther King, Jr., day is celebrated as a federal holiday for the first time.
- 1987 - Church of England envoy Terry Waite is kidnapped in Lebanon.
- 1990 - Black January - crackdown of Azerbaijani pro-independence demonstrations by Soviet army in Baku.
- 1991 - Sudan's government imposes Islamic law nationwide, worsening the civil war between the country's Muslim north and Christian south.
- 1992 - Air Inter Flight 148 crashes near Strasbourg, France, killing 82 passengers and 5 crew.
- 1999 - The China News Service announces new government restrictions on Internet use aimed especially at Internet cafés.
- 2001 - Philippine president Joseph Estrada is ousted in a nonviolent 4-day revolution, and is succeeded by Gloria Macapagal-Arroyo.
- 225 - Gordian III, Roman Emperor (d. 244)
- 1292 - Elisabeth I of Bohemia (d. 1330)
- 1358 - Eleanor of Aragon, wife of John I of Castile (d. 1382)
- 1435 - Ashikaga Yoshimasa, Japanese shogun (d. 1490)
- 1554 - King Sebastian of Portugal (d. 1578)
- 1586 - Johann Schein, German composer (d. 1630)
- 1664 - Giovanni Vincenzo Gravina, Italian writer and jurist (d. 1718)
- 1716 - King Charles III of Spain (d. 1788)
- 1716 - Jean-Jacques Barthélemy, French writer and numismatist (d. 1795)
- 1775 - André-Marie Ampère, French physicist (d. 1836)
- 1781 - Joseph Hormayr Freiherr zu Hortenburg, Austrian politician (d. 1848)
- 1783 - Justus Johann Friedrich Dotzauer, German cellist and composer (d. 1860)
- 1798 - Anson Jones, 5th and last President of Texas (d. 1858)
- 1804 - Eugène Sue, French novelist (d. 1857)
- 1812 - Thomas Meik, Scottish engineer (d. 1896)
- 1834 - George D. Robinson, 34th Governor of Massachusetts (d. 1896)
- 1837 - David Josiah Brewer, U.S. Supreme Court Justice (d. 1910)
- 1855 - Ernest Chausson, French composer (d. 1899)
- 1867 - Yvette Guilbert, French singer and actress (d. 1944)
- 1873 - Johannes Vilhelm Jensen, Danish Nobel laureate (d. 1950)
- 1876 - Józef Hofmann, Polish pianist (d. 1967)
- 1878 - Finlay Currie, British actor (d. 1968)
- 1878 - Ruth St. Denis, American dancer (d. 1968)
- 1880 - Walter W. Bacon, American politician (d. 1962)
- 1889 - Allan Haines Loughead, American aviation executive (d. 1969)
- 1891 - Mischa Elman, Ukrainian born violinist (d. 1967)
- 1893 - Georg Åberg, Swedish athlete (d. 1946)
- 1894 - Walter Piston, American composer (d. 1976)
- 1896 - George Burns, American actor, comedian (d. 1996)
- 1896 - Isabel Withers, American actress (d. 1968)
- 1898 - U Razak, Burmese politician (d. 1947)
- 1899 - Kenjiro Takayanagi, Japanese development of television (d. 1990)
- 1900 - Colin Clive, British actor (d. 1937)
- 1902 - Leon Ames, American actor (d. 1993)
- 1907 - Paula Wessely, Austrian actress (d. 2000)
- 1910 - Joy Adamson, Austrian naturalist and writer (d. 1980)
- 1912 - Walter Briggs, Jr., American sports executive (d. 1970)
- 1915 - Ghulam Ishaq Khan, President of Pakistan (d. 2006)
- 1919 - Juan García Esquivel, Mexican bandleader (d. 2002)
- 1920 - Federico Fellini, Italian film director (d. 1993)
- 1920 - DeForest Kelley, American actor (d. 1999)
- 1920 - Thorleif Schjelderup, Norwegian author and ski jumper (d. 2006)
- 1921 - Telmo Zarraonaindía, Spanish footballer (d. 2006)
- 1922 - Ray Anthony, American trumpeter, bandleader and actor
- 1922 - Graham Stark, British actor
- 1923 - Nora Brockstedt, Norwegian singer
- 1924 - Slim Whitman, American singer
- 1925 - Ernesto Cardenal, Nicaraguan theologian and politician
- 1926 - Jamiluddin Aali, Pakistani poet, essayist and columnist
- 1926 - Qurratulain Hyder, Pakistani novelist (d. 2007)
- 1926 - Patricia Neal, American actress
- 1926 - David Tudor, American pianist and composer (d. 1996)
- 1929 - Jimmy Cobb, American jazz drummer
- 1929 - Arte Johnson, American actor
- 1929 - Glenn Roberts, American race car driver (d. 1964)
- 1930 - Buzz Aldrin, American astronaut
- 1931 - David Lee, American physicist, Nobel Prize in Physics laureate
- 1931 - Hachidai Nakamura, Japanese songwriter and pianist (d. 1992)
- 1932 - Lou Fontinato, Canadian ice hockey player
- 1933 - Ron Townson, American singer (The Fifth Dimension) (d. 2001)
- 1934 - Tom Baker, British actor
- 1935 - Joan Weston, Roller Derby Queen (d. 1997)
- 1937 - Dorothy Provine, American singer, dancer and actress
- 1938 - William Berger, Austrian actor (d. 1993)
- 1938 - Derek Dougan, Northern Irish footballer (d. 2007)
- 1939 - Paul Coverdell, American politician (d. 2000)
- 1940 - Carol Heiss, American figure skater
- 1940 - Krishnam Raju, Indian actor and politician
- 1941 - Pierre Lalonde, Quebec singer and television host
- 1943 - Farhad Mehrad, Iranian musician
- 1944 - José Luis Garci, Spanish filmmaker
- 1945 - Robert Olen Butler, American writer
- 1945 - Christopher Martin-Jenkins, cricket commentator and correspondent
- 1945 - Eric Stewart, English musician and songwriter (10cc)
- 1946 - David Lynch, American film director
- 1947 - Cyrille Guimard, French cyclist and directeur sportif
- 1948 - Natan Sharansky, Russian-born physicist and politician
- 1948 - Nancy Kress, American writer
- 1949 - Göran Persson, Prime Minister of Sweden
- 1950 - Liza Goddard, British actress
- 1950 - Edward Hirsch. American poet
- 1950 - Chuck Lefley, Canadian ice hockey player
- 1950 - Mahamane Ousmane, President of Niger
- 1951 - Ivan Fischer, Hungarian conductor
- 1951 - Ian Hill, British musician (Judas Priest)
- 1952 - Paul Stanley, American musician (Kiss)
- 1955 - Wyatt Knight, American actor
- 1955 - Joe Doherty, Provisional Irish Republican Army member
- 1955 - Hiromi Ōta, Japanese singer
- 1956 - Maria Larsson, Swedish politician
- 1956 - Bill Maher, American actor, comedian, and political analyst
- 1958 - Lorenzo Lamas, American actor
- 1960 - Scott Thunes, American musician (Frank Zappa)
- 1960 - Will Wright, American computer game designer
- 1963 - James Denton, American actor
- 1962 - IKKO, Japanese make-up artist
- 1963 - Firebreaker Chip, American professional wrestler
- 1964 - Ozzie Guillén, Venezuelan-born baseball player and manager
- 1964 - Ron Harper, American basketball player
- 1964 - Kazushige Nojima, Japanese game scenario writer
- 1965 - Colin Calderwood, Scottish footballer
- 1965 - Greg Kriesel, American bassist (The Offspring)
- 1965 - Sophie, The Countess of Wessex, the wife of Prince Edward, Earl of Wessex
- 1965 - John Michael Montgomery, American singer
- 1965 - Anton Weissenbacher, Romanian footballer
- 1966 - Stacey Dash, American actress
- 1966 - Tracii Guns, American guitarist
- 1968 - Melissa Rivers, American reporter and actress
- 1968 - Nick Anderson, American basketball player
- 1968 - Rainn Wilson, American actor
- 1969 - Patrick K. Kroupa, American computer hacker
- 1969 - Nicky Wire, British Musician (Manic Street Preachers)
- 1970 - Mitch Benn, UK comedian, songwriter, actor
- 1970 - Kerri Kenney-Silver, American actress
- 1970 - Skeet Ulrich, American actor
- 1971 - Derrick Green, American singer (Sepultura)
- 1971 - Gary Barlow, English singer (Take That)
- 1971 - Ahmir "?uestlove" Thompson, American drummer (The Roots)
- 1971 - Brian Giles, American baseball player
- 1973 - Princess Mathilde, Duchess of Brabant
- 1974 - David Dei, Italian footballer
- 1975 - David Eckstein, American baseball player
- 1975 - Norberto Fontana, Argentine racing driver
- 1976 - Gretha Smit, Dutch speed skater
- 1977 - Melody, Belgian singer
- 1978 - Joy Giovanni, American actress and glamour model
- 1978 - Sonja Kesselschläger, German heptathlete
- 1978 - Allan Søgaard, Danish footballer
- 1979 - Rob Bourdon, American musician (Linkin Park)
- 1979 - Asaka Kubo, Japanese gravure idol of 20th Century
- 1979 - Will Young, British singer
- 1980 - Philippe Cousteau Jr., Freanch oceanographer; grandson of Jacques Cousteau
- 1980 - Brigitte Olivier, Belgian judoka
- 1980 - Matthew Tuck, Welsh guitarist (Bullet for My Valentine)
- 1981 - Freddy Guzmán, Dominican baseball player
- 1981 - Jason Richardson, American basketball player
- 1981 - Christine Bleakley, British television presenter
- 1981 - Owen Hargreaves, English footballer
- 1981 - Crystal Lowe, Canadian actress
- 1982 - Joe Swash, English actor
- 1983 - Geovany Soto, Puerto Rican baseball player
- 1983 - Paula Taylor, English-Thai actress, model and presenter
- 1983 - Mari Yaguchi, Japanese singer (Morning Musume)
- 1984 - Olivia Hallinan, English actress
- 1984 - Toni Gonzaga, Filipina actress and singer
- 287 - St. Sebastian
- 1156 - Bishop Henry, patron saint of Finland
- 1191 - Frederick VI, Duke of Swabia (b. 1167)
- 1479 - King John II of Aragon (b. 1397)
- 1568 - Myles Coverdale, English Bible translator
- 1612 - Rudolf II, Holy Roman Emperor (b. 1552)
- 1666 - Anna of Austria, wife of Louis XIII of France and regent (b. 1601)
- 1707 - Humphrey Hody, English theologian (b. 1659)
- 1709 - François de la Chaise, French confessor of Louis XIV of France (b. 1624)
- 1739 - Francesco Galli-Bibiena, Italian architect/designer (b. 1659)
- 1751 - John Hervey, 1st Earl of Bristol, English politician (b. 1665)
- 1770 - Charles Yorke, Lord Chancellor of Great Britain (b. 1722)
- 1779 - David Garrick, English actor (b. 1717)
- 1810 - Benjamin Chew, Chief Justice of colonial Pennsylvania (b. 1722)
- 1819 - King Charles IV of Spain (b. 1748)
- 1848 - Christian VIII of Denmark (b. 1786)
- 1850 - Adam Oehlenschläger, Danish poet (b. 1779)
- 1873 - The Venerable Father Basil Anthony Marie Moreau, Founder of the Congregation of Holy Cross (b. 1799)
- 1875 - Jean-François Millet, French painter (b. 1814)
- 1891 - David Kalakaua, King of Hawaii (b. 1836)
- 1900 - John Ruskin, art critic (b. 1819)
- 1901 - Zénobe Gramme, Belgian engineer (b. 1826)
- 1920 - Georg Lurich, Estonian wrestler (b. 1876)
- 1936 - King George V of the United Kingdom (b. 1865)
- 1940 - Omar Bundy, U.S. army general (b. 1861)
- 1944 - James McKeen Cattell, American psychologist (b. 1860)
- 1947 - Josh Gibson, African-American baseball player (b. 1911)
- 1954 - Fred Root, English cricketer (b. 1890)
- 1962 - Robinson Jeffers, American poet (b. 1887)
- 1965 - Alan Freed, American disk jockey (b. 1922)
- 1971 - Gilbert M. 'Broncho Billy' Anderson, American actor, director, writer, and producer (b. 1880)
- 1973 - Lorenz Böhler, Austrian physician (b. 1885)
- 1979 - Gustav Winckler, Danish singer (b. 1925)
- 1983 - Garrincha, Brazilian footballer (b. 1933)
- 1984 - Johnny Weissmuller, American swimmer and actor (b. 1904)
- 1988 - Khan Abdul Ghaffar Khan, Pashtun Nationalist & non-violent freedom fighter (b. 1890)
- 1988 - Dora Stratou, Greek choreographer and folklorist (b. 1903)
- 1989 - Alamgir Kabir, Bangladeshi film director (b. 1938)
- 1990 - Hayedeh, Persian singer (b. 1942)
- 1990 - Barbara Stanwyck, American actress (b. 1907)
- 1993 - Audrey Hepburn, Anglo-Dutch actress (b. 1929)
- 1994 - Sir Matt Busby, Scottish football player and coach (b. 1909)
- 1996 - Gerry Mulligan, American musician (b. 1927)
- 1997 - Curt Flood, baseball player (b. 1938)
- 1998 - Bobo Brazil, American professional wrestler (b. 1924)
- 2002 - Carrie Hamilton, actress and singer (b. 1963)
- 2003 - Al Hirschfeld, American caricaturist (b. 1903)
- 2003 - Craig Kelly, American snowboarder (b. 1966)
- 2003 - Nedra Volz, American actress (b. 1908)
- 2003 - Bill Werbeniuk, Canadian snooker player (b. 1947)
- 2004 - Guinn Smith, American athlete (b. 1920)
- 2005 - Per Borten, Prime Minister of Norway (b. 1913)
- 2005 - Roland Frye, American literary critic and theologian (b. 1921)
- 2005 - Jan Nowak-Jeziorański, Polish journalist, writer, and politician (b. 1913)
- 2005 - Miriam Louisa Rothschild, British zoologist, entomologist, and author (b. 1908)
