2004 was designated as the International Year of Rice and the International Year to Commemorate the Struggle Against Slavery and its Abolition.
- January 3 - Flash Airlines Flight 604 crashes into the Red Sea off the coast of Egypt, killing all 148 aboard making it one of the deadliest aviation accidents in Egyptian history at the time.
- January 4 - NASA's MER-A spacecraft landed on the surface of Mars.
- January 8 - The RMS Queen Mary 2, the largest ocean liner ever built, is christened by its namesake's granddaughter, Queen Elizabeth II.
- January 25 - NASA's MER-B spacecraft has landed on the surface of Mars.
- February 4 - Mark Zuckerberg creates the social networking site Facebook.
- February 26 - Macedonian president Boris Trajkovski is killed in a plane crash near Mostar, Bosnia and Herzegovina.
- February 29 - Haitian president Jean-Bertrand Aristide is overthrown in a coup d'état.
- March 2 - A series of bombings occur in Karbala, Iraq, killing over 140 Shia Muslims commemorating the Day of Ashura.
- March 11 - Coordinated bombings at a Cercanías train station in Madrid, Spain, kill at least 192 people.
- March 14 - The PSOE wins the election in Spain; José Luis Rodríguez Zapatero is elected Prime Minister of Spain, replacing José María Aznar.
- March 28 - Hurricane Catarina, the first ever recorded South Atlantic tropical cyclone, makes landfall in Santa Catarina, Brazil.
- March 29 - Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia are admitted to NATO, the largest expansion of the organization.
- April 8 - The Humanitarian Ceasefire Agreement is signed by the Sudanese government and two rebel groups, in order to put a pause on the War in Darfur.
- April 17 - Israeli helicopters fire missiles at a convoy of vehicles in the Gaza Strip, killing Hamas leader Abdel Aziz al-Rantisi.
- April 24 - Referendums on the Annan Plan for Cyprus, which proposes to reunite the island, take place in both the Greek-controlled and the Turkish-controlled parts. Although the Turkish Cypriots vote in favour, the Greek Cypriots reject the proposal.
- May 1 - The European Union expands by 10 member states: Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia.
- May 12–15 – The Eurovision Song Contest 2004 takes place in Istanbul, Turkey, and is won by Ukrainian entrant Ruslana with the song "Wild Dances".
- June 8 - 2004 transit of Venus.
- June 12 - July 4 - Portugal hosts the UEFA Euro 2004 football tournament, which is won by Greece.
- June 21 - In Mojave, California, SpaceShipOne becomes the first privately funded spaceplane to achieve spaceflight.
- June 28 - The U.S.-led coalition occupying Iraq, the Coalition Provisional Authority, transfers sovereignty to the Iraqi Interim Government.
- June 30 - Preliminary hearings begin in Iraq in the trial of president Saddam Hussein, for war crimes and crimes against humanity.
- July 1 - The unmanned Cassini–Huygens spacecraft arrives at Saturn.
- July 11 - The Russian Federation stops recognizing Soviet Union passports as legal identification.
- August 1 – A fire in the "Ycua Bolaños-Botánico" supermarket in Asunción, Paraguay kills around 400 people.
- August 3 - NASA's unmanned MESSENGER spacecraft is launched, with its primary mission being the study of Mercury.
- August 12 - Lee Hsien Loong is sworn in as the third Prime Minister of Singapore.
- August 13-29 - The 2004 Summer Olympics are held in Athens, Greece.
- August 22 - Armed robbers steal Edvard Munch's The Scream, Madonna, and other paintings from the Munch Museum in Oslo, Norway.
- August 24 - After departing Domodedovo International Airport in Moscow, Volga-AviaExpress Flight 1303, a Tupolev Tu-134, explodes over Russia's Tula Oblast and crashes, killing all 43 people on board; minutes later, Siberia Airlines Flight 1047, a Tupolev Tu-154 departing the same airport, explodes over Rostov Oblast and crashes, killing all 46 on board. The Government of Russia declares the explosions to have been caused by female Chechen suicide bombers.
- September 1 - Chechen rebels take 1,128 people hostage, mostly children, at a school in Beslan, Russia. The crisis ends when Russian security forces storm the building, resulting in more than 330 people being killed..
- September 9 - A car bomb of the Jemaah Islamiya exploded at the Australian embassy in Jakarta, Indonesia, killing 9 people.
- October 8 - Suicide bombers detonate two bombs at the Red Sea resort of Taba, Egypt, killing 34 people and injuring 171, mostly Israeli tourists.
- October 9 - 2004 Australian federal election: John Howard's Liberal/National Coalition Government is re-elected with an increased majority, defeating the Labor Party led by Mark Latham.
- October 19 - A team of explorers reach the bottom of Krubera Cave, the world's deepest cave, with a depth of 2,080 meters.
- October 20 - Susilo Bambang Yudhoyono is sworn in as the 6th President of Indonesia, becoming the first directly elected president in Indonesia.
- October 29 - European heads of state sign in Rome the Treaty and Final Act, establishing the first European Constitution.
- November 2 - George W. Bush is reelected President of the United States.
- November 13 - The European Space Agency unmanned probe SMART-1 arrives at the Moon, becoming the first European satellite to fly to the Moon and orbit it.
- November 16 - NASA's hypersonic Scramjet breaks a record by reaching a velocity of about 7,000 mph in an unmanned experimental flight.
- November 21 - The Nintendo DS, the best selling handheld game console of all time, is released in North America.
- November 22 - The Orange Revolution begins following a disputed presidential election in Ukraine where Viktor Yanukovych won against Viktor Yushchenko amid accusations of electoral fraud. A revote results in Yushchenko being declared the winner.
- December 14 - The world's tallest bridge, the Millau Viaduct over the Tarn in the Massif Central mountains, France, is officially opened.
- December 21 - Iraqi insurgents attack a U.S. military base in the city of Mosul, killing 22 people.
- December 26 - The 9.1–9.3 Indian Ocean earthquake shakes northern Sumatra with a maximum Mercalli intensity of IX. One of the largest observed tsunamis follows, affecting coastal areas of Thailand, India, Sri Lanka, the Maldives, Malaysia, Myanmar, Bangladesh, and Indonesia, killing over 200,000 people.
- December 27 - Astrophysicists from the Max Planck Institute for Extraterrestrial Physics in Garching near Munich measure the strongest burst from a magnetar. At 21:30:26 UT Earth is hit by a huge wave front of gamma and X-rays. It is the strongest flux of high-energetic gamma radiation measured so far.
- December 30 – A fire in the República Cromañón nightclub in Buenos Aires, Argentina kills 194.
- December 31 - Taipei 101, at the time the tallest skyscraper in the world, standing at a height of, officially opens.
- Time Warner completes its sale of the Warner Music Group, finally cutting down its debt.
- January 4 - Peyton Kennedy, Canadian actress
- January 15 - Grace VanderWaal, American singer-songwriter
- January 21 - Princess Ingrid Alexandra of Norway
- January 28 - Emoni Bates, American basketball player
- February 1 - Ashley Gerasimovich, American actress
- February 19 - Millie Bobby Brown, British actress
- March 5 - Choi Soo-in, South Korean child actress
- March 13 - Coco Gauff, American tennis player
- March 27 - Amira Willighagen, Dutch singer
- April 14 - Anastasia Tarakanova, Russian figure skater
- April 16 - Elha Nympha, Filipino singer
- April 22 - Teagan Croft, Australian actress
- May 1 - Charli D'Amelio, American dancer and social media personality.
- May 4 - Kanon Tani, Japanese actress
- May 22 - Peyton Elizabeth Lee, American actress
- May 27 - You Young, South Korean figure skater
- June 1 - Miyu Honda, Japanese actress
- June 3 - Ryan Gray, Canadian Singer
- June 4 - Mackenzie Ziegler, American dancer
- June 8 - Francesca Capaldi, American actress
- June 15 - Sterling Jerins, American actress
- June 17 - Fuku Suzuki, Japanese actor and singer
- June 23
- * Alexandra Trusova, Russian figure skater
- * Mana Ashida, Japanese actress
- August 14 - Marsai Martin, American actress
- September 23 - Anthony Gonzalez, American actor
- September 25 - Seiran Kobayashi, Japanese actress
- October 3 - Noah Schnapp, American actor
- October 5 - Choi Kwon-soo, South Korean actor
- October 6 - Bronny James, American basketball player
- October 10 - Zain Al Rafeea, Syrian-born actor
- October 12 - Darci Lynne, American ventriloquist
- November 11 - Oakes Fegley, American actor
- December 6 - Lala Kramarenko, Russian gymnast
- January 4 - Joan Aiken, English writer
- January 6 - Pierre Charles, 5th Prime Minister of Dominica
- January 7 - Ingrid Thulin, Swedish actress
- January 9 - Norberto Bobbio, Italian philosopher
- January 13 - Harold Shipman, British serial killer
- January 14
- * Terje Bakken, Norwegian musician
- * Uta Hagen, American actress
- January 16 - Kalevi Sorsa, Finnish politician, 34th Prime Minister of Finland
- January 17 - Czesław Niemen, Polish singer-songwriter
- January 22 - Ann Miller, American dancer and actress
- January 23 - Helmut Newton, German-Australian photographer
- January 25
- * Fanny Blankers-Koen, Dutch athlete
- * Miklós Fehér, Hungarian footballer
- January 27 - Jack Paar, American author, actor, radio comedian, and talk show host
- January 28 - Joe Viterelli, American actor
- February 14 - Marco Pantani, Italian cyclist
- February 17 - José López Portillo, 51st President of Mexico
- February 21 - John Charles, Welsh footballer
- February 24 - John Randolph, American actor
- February 26
- * Adolf Ehrnrooth, Finnish general
- * Boris Trajkovski, 2nd president of the Republic of Macedonia
- February 27 - Paul Sweezy, American economist and editor
- February 28 - Daniel J. Boorstin, American historian and Librarian of Congress
- February 29 - Harold Bernard St. John, 3rd Prime Minister of Barbados
- March 2 - Mercedes McCambridge, American actress
- March 4 - Claude Nougaro, French singer
- March 5 - Carlos Julio Arosemena Monroy, 31st President of Ecuador
- March 7 - Paul Winfield, American actor
- March 8
- * Tichi Wilkerson Kassel, American film personality and publisher
- * Muhammad Zaidan, founder of the Palestine Liberation Front
- March 15 - John Pople, English Nobel chemist
- March 18 - Abdujalil Samadov, 4th Prime Minister of Tajikistan
- March 20 - Juliana, Queen regnant of the Netherlands
- March 22 - Ahmed Yassin, Palestinian co-founder of Hamas
- March 27 - Adán Sánchez, Mexican singer
- March 28 - Peter Ustinov, English actor and director
- March 29 - Lise de Baissac, British secret agent
- April 1 - Carrie Snodgress, American actress
- April 18 - Kamisese Mara, 1st Prime Minister and 2nd president of Fiji
- April 19 – John Maynard Smith, English biologist
- April 22 - Pat Tillman, American football player
- April 24 - Estée Lauder, American cosmetics entrepreneur
- April 26 - Hubert Selby, Jr., American writer
- May 4 - David Reimer, Canadian victim of a botched circumcision and transgender reassignment surgery
- May 5 - Ritsuko Okazaki, Japanese songwriter
- May 6 - Barney Kessel, American jazz guitarist
- May 7
- * Nicholas Berg, American businessman
- * Oliver David Jackson, brigadier of Australian Army
- May 9 - Alan King, American actor and comedian
- May 14 - Anna Lee, British-born American actress
- May 16 - Marika Rökk, Egyptian-born Austrian singer, dancer and actress
- May 17
- * Tony Randall, American actor
- * Ezzedine Salim, 45th Prime Minister of Iraq
- May 18 - Elvin Jones, American jazz drummer
- May 29 - Archibald Cox, American lawyer and professor
- June 1 - William Manchester, American historian
- June 2
- * Dom Moraes, Indian poet and writer
- * Tesfaye Gebre Kidan, Ethiopian general, defense minister and acting president of Ethiopia
- June 3 - Quorthon, Swedish singer, songwriter, musician and record producer
- June 4 - Steve Lacy, American jazz soprano saxophonist
- June 5 - Ronald Reagan, American politician and actor, 40th President of the United States
- June 10
- * Ray Charles, American singer and musician
- * Xenophon Zolotas, Greek economist and politician, interim Prime Minister of Greece
- June 16 - Thanom Kittikachorn, Thai military general, 10th Prime Minister of Thailand
- June 22 – Thomas Gold, American astrophysicist
- June 26 - Naomi Shemer, Israeli songwriter
- July 1 - Marlon Brando, American actor
- July 5
- * Hugh Shearer, Jamaican politician, 3rd Prime Minister of Jamaica
- * Rodger Ward, American race car driver
- July 6
- * Eric Douglas, American actor
- * Thomas Klestil, Austrian politician and diplomat, 10th President of Austria
- July 10
- * Isabel Sanford, American actress
- * Maria de Lourdes Pintasilgo, 108th Prime Minister of Portugal
- July 13 - Carlos Kleiber, Austrian conductor
- July 16 - Charles Sweeney, American WWII pilot
- July 19 - Zenkō Suzuki, Japanese politician, 44th Prime Minister of Japan
- July 21
- * Jerry Goldsmith, American composer
- * Edward B. Lewis, American Nobel geneticist
- July 22 - Sacha Distel, French singer
- July 28 - Francis Crick, English Nobel molecular biologist
- July 31 - Virginia Grey, American actress
- August 1 - Philip Abelson, American Nobel physicist
- August 3 - Henri Cartier-Bresson, French photographer
- August 6 - Rick James, American musician
- August 8 - Fay Wray, Canadian-American actress
- August 12 - Godfrey Hounsfield, English Nobel electrical engineer and inventor
- August 13 - Julia Child, American chef
- August 14 - Czesław Miłosz, Polish-born Nobel writer
- August 15 - Sune Bergström, Swedish Nobel biochemist
- August 17 - Frank Cotroni, Canadian mobster
- August 18 - Elmer Bernstein, American composer
- August 24 - Elisabeth Kübler-Ross, Swiss-born psychiatrist
- August 26 - Laura Branigan, American singer
- August 29 - Leonardus Benjamin Moerdani, Indonesian military force commander
- August 30 - Fred Lawrence Whipple, American astronomer
- September 8 – Frank Thomas, American animator and pianist
- September 11 - Patriarch Peter VII of Alexandria
- September 13 - Luis E. Miramontes, Mexican chemist
- September 15
- * Johnny Ramone, American guitarist
- * Daouda Malam Wanké, 6th President of Niger
- September 18 - Russ Meyer, American director and photographer
- September 19 - Skeeter Davis, American country music singer-songwriter
- September 20 - Brian Clough, British football manager
- September 22
- * Winston Cenac, 3rd Prime Minister of Saint Lucia
- * Ray Traylor Jr., American professional wrestler
- September 24 - Françoise Sagan, French writer
- October 1 - Richard Avedon, American photographer
- October 3 - Janet Leigh, American actress
- October 4 - Gordon Cooper, American astronaut
- October 5
- * Rodney Dangerfield, American comedian and actor
- * Maurice Wilkins, New Zealand-born Nobel physicist
- October 8 - Jacques Derrida, Algerian-born French literary critic
- October 10 - Christopher Reeve, American actor and activist
- October 11 - Keith Miller, Australian sportsman
- October 17 - Julius Harris, American actor
- October 23 - Bill Nicholson, English footballer, coach and manager
- October 25 - John Peel, British radio disc jockey
- October 29 - Princess Alice, Duchess of Gloucester
- November 1 - Mac Dre, American rapper
- November 2
- * Theo van Gogh, Dutch film director
- * Zayed bin Sultan Al Nahyan, 1st president of the United Arab Emirates
- November 3 - Sergejs Žoltoks, Latvian hockey player
- November 7 - Howard Keel, American singer and actor
- November 9
- * Iris Chang, American journalist
- * Emlyn Hughes, English footballer
- * Stieg Larsson, Swedish writer
- November 11 - Yasser Arafat, Palestinian Nobel leader
- November 13 - Ol' Dirty Bastard, American rapper
- November 17 - Alexander Ragulin, Russian ice hockey player
- November 19 - John Vane, British Nobel pharmacologist
- November 23 - Rafael Eitan, Israeli politician
- November 26 - Philippe de Broca, French film director
- November 29
- * Yvonne Aitken, Australian botanist
- * John Drew Barrymore, American actor
- December 1 - Prince Bernhard of Lippe-Biesterfeld, Prince consort of the Netherlands
- December 8 - Dimebag Darrell, American guitarist
- December 19
- * Herbert C. Brown, English-born Nobel chemist
- * Renata Tebaldi, Italian soprano
- December 23 - P. V. Narasimha Rao, Indian politician, 10th Prime Minister of India
- December 28
- * Jerry Orbach, American actor
- * Susan Sontag, American writer and activist
- December 29 - Julius Axelrod, American biochemist and academic, Nobel Prize laureate
- December 30 - Artie Shaw, American musician
- December 31 - Gérard Debreu, French-born Nobel economist
- Chemistry - Aaron Ciechanover, Avram Hershko, Irwin Rose
- Economics - Finn E. Kydland, Edward C. Prescott
- Literature - Elfriede Jelinek
- Peace - Wangari Maathai
- Physics - David J. Gross, H. David Politzer, Frank Wilczek
- Physiology or Medicine - Linda B. Buck, Richard Axel
New English words and terms
- life hack
- Silver Alert
- social media