1844 (MDCCCXLIV) was a leap year starting on Monday of the Gregorian calendar and a leap year starting on Saturday of the Julian calendar, the 1844th year of the Common Era (CE) and Anno Domini (AD) designations, the 844th year of the 2nd millennium, the 44th year of the 19th century, and the 5th year of the 1840s decade. As of the start of 1844, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.
- January 15 – The University of Notre Dame, based in the city of the same name, receives its charter from Indiana.
- February 27 – The Dominican Republic gains independence from Haiti.
- February 28 – A gun on the USS Princeton explodes while the boat is on a Potomac River cruise, killing 2 United States Cabinet members and several others.
- March 8 – King Oscar I ascends to the throne of Sweden–Norway upon the death of his father, Charles XVI/III John.
- March 12 – The Columbus and Xenia Railroad, the first railroad planned to be built in Ohio, is chartered.
- March 21 – The Bahá'í calendar begins.
- March 23 – The Edict of Toleration is passed, allowing Jews to settle in the Holy Land.
- April 2 – The Fleet Prison for debtors in London is closed, marking a significant milestone in the country's human rights record.
- May 1 – The Hong Kong Police Force, the world's second, Asia's first modern police force, is established.
- May 23 – Persian Prophet The Báb privately announces his revelation to Mullá Husayn, just after sunset, founding the Bábí faith (later evolving into the Bahá'í Faith as the Báb intended) in Shiraz, Persia (now Iran). Contemporaneously, on this day in nearby Tehran, was the birth of `Abdu'l-Bahá; the eldest Son of Bahá'u'lláh, Prophet-Founder of the Bahá'í Faith, the inception of which, the Báb's proclaimed His own mission was to herald. `Abdu'l-Bahá Himself was later proclaimed by Bahá'u'lláh to be His own successor, thus being the third "central figure" of the Bahá'í Faith.
- May 24 – The first electrical telegram is sent by Samuel Morse from the U.S. Capitol in Washington, D.C. to the B&O Railroad "outer depot" in Baltimore, saying "What hath God wrought".
- June–July– The Great Flood of 1844 hits the Missouri River and Mississippi River.
- June 6 – George Williams sets up (in London) what is often cited as the first youth organisation in the world - "The Young Men's Christian Association", commonly known as YMCA. It would grow to a worldwide organisation based in Geneva, Switzerland, with more than 57 million beneficiaries from 125 national associations. George Williams aimed to put Christian principles into practice by developing a healthy "body, mind, and spirit." These three angles are reflected by the different sides of the (red) triangle—part of all YMCA logos.
- June 15 – Charles Goodyear receives a patent for vulcanization, a process to strengthen rubber.
- June 22 The Delta Kappa Epsilon fraternity is founded. ΔΚΕ will be home to many well known VIPs, such as U.S. Presidents George W. Bush, George H. W. Bush, Gerald Ford, and Theodore Roosevelt.
- June 27 – Joseph Smith, founder of the Latter Day Saint movement, and his brother Hyrum, are killed in Carthage Jail, Carthage, Illinois by an armed mob, leading to a Succession crisis. John Taylor, future president of The Church of Jesus Christ of Latter-day Saints, is severely injured but survives.
- July 3
- August 8 – During a meeting held in Nauvoo, Illinois, the Quorum of the Twelve, headed by Brigham Young, is chosen as the leading body of The Church of Jesus Christ of Latter-day Saints.
- August 14 – Abdelkader El Djezairi is defeated at Isly in Morocco; sultan Abd al-Rahman of Morocco soon repudiates his ally.
- August 16 – Narciso Claveria, Governor-General of the Philippines, makes a decree announcing that Monday, December 30, 1844 will be immediately followed by Wednesday, January 1, 1845. (Tuesday, December 31, 1844 was removed from the Philippine calendar because from 1521-1844, the Philippines was one day behind its Asian neighbors).
- August 28 – Friedrich Engels and Karl Marx meet in Paris, France.
- September 25–September 27 – The first ever international cricket match is played in New York City, United States v Canadian Provinces.
- October 22 – This second date, predicted by the Millerites for the Second Coming of Jesus, leads to the Great Disappointment. The Seventh-day Adventist Church believes this date to be the starting point of the Investigative judgment, just prior to the Second Coming of Jesus, as declared in the 26th of 28 fundamental doctrines of Seventh-day Adventists.
- October 23 – The Báb is publicly proclaimed to be the promised one of Islam (the Qá'im, or Mahdi). He is also considered to be simultaneously the return of Elijah, John the Baptist, and the "Ushídar-Máh" referred to in the Zoroastrian scriptures. He announces to the world the coming of "He whom God shall make manifest". He is considered the forerunner of Bahá'u'lláh – the founder of the Bahá'í Faith – whose claims include being the return of Jesus.
- November 3 – Giuseppe Verdi's I due Foscari debuts at Teatro Argentina, Rome.
- November 6 – The Dominican Republic drafts its first Constitution.
- December 4 – U.S. presidential election, 1844: James K. Polk defeats Henry Clay.
- December 21 – The Rochdale Pioneers commence business at their cooperative in Rochdale, England.
- Swedish chemistry professor Gustaf Erik Pasch invents the safety match.
- Carlos Antonio López becomes dictator of Paraguay.
- The anonymously written Vestiges of the Natural History of Creation is published, and paves the way for the acceptance of Darwin's book On the Origin of Species.
- The Free Church Institution is established by Reverend Alexander Duff in Calcutta, India. This is later merged with the General Assembly's Institution to form the Scottish Church College, one of the pioneering institutions that ushers in the Bengali renaissance.
- Annual British iron production reaches 3 million tons.
- In Munich the Feldherrnhalle is completed.
- January 7 – Bernadette Soubirous, French visionary from Lourdes (d. 1879)
- January 9 – Julián Gayarre, Spanish opera singer (d. 1890)
- February 17 – Aaron Montgomery Ward, American department store founder (d. 1913)
- February 20
- February 14 – Robert Themptander, 4th Prime Minister of Sweden (d. 1897)
- February 21 – Charles-Marie Widor, French organist, composer (d. 1937)
- February 26 – Horace Harmon Lurton, Associate Justice of the Supreme Court of the United States (d. 1914)
- February 28 – French Ensor Chadwick, American admiral (d. 1919)
- March 10 – Pablo de Sarasate, Spanish violinist (d. 1908)
- March 18 – Nikolai Rimsky-Korsakov, Russian composer (d. 1908)
- March 25 – Adolf Engler, German botanist (d. 1930)
- March 30 – Paul Verlaine, French poet (d. 1896)
- April 1 – Nikolai Skrydlov, Russian admiral (d. 1918)
- April 13 – John Surratt, suspect in the Abraham Lincoln assassination, son of Mary Surratt (d. 1916)
- April 16 – Anatole France, French writer, Nobel Prize laureate (d. 1924)
- April 22 – Lewis Powell, attempted assassin of United States Secretary of State William H. Seward, conspirator with John Wilkes Booth (d. 1865)
- April 26 – Lizardo García, 17th President of Ecuador (d. 1937)
- April 28 – Katarina Milovuk, Serbian educator, women's rights activist (d. 1909)
- May 3
- May 14 – Alexander Kaulbars, Russian general, explorer (d. 1925)
- May 17 – Julius Wellhausen, German biblical scholar (d. 1918)
- May 19 – William M. Folger, American admiral (d. 1928)
- May 21 – Henri Rousseau, French artist (d. 1910)
- May 22 – Mary Cassatt, American artist (d. 1926)
- May 23 – `Abdu'l-Bahá, Persian Bahá'í religious leader (d. 1921)
- June 3 – Garret Hobart, 24th Vice President of the United States (d. 1899)
- June 28 – John Boyle O'Reilly, Irish-born poet, journalist and fiction writer (d. 1890)
- July 9 – Charles D. Barney, American stockbroker (d. 1945)
- July 11 – King Peter I of Serbia (d. 1921)
- July 22 – William Archibald Spooner, British scholar, Anglican priest (d. 1930)
- July 25 – Thomas Eakins, American painter, sculptor (d. 1916)
- July 28 – Gerard Manley Hopkins, English poet (d. 1889)
- July 30 – Robert Jones Burdette, American minister, sentimental humorist (d. 1914)
- August 5
- August 6 – Alfred, Duke of Saxe-Coburg and Gotha (d. 1900)
- August 17 – Menelik II, Emperor of Ethiopia (d. 1913)
- August 20 – Mutsu Munemitsu, Japanese statesman, diplomat (d. 1897)
- August 22 – George Washington DeLong, American naval officer, explorer (d. 1881)
- August 23 – Hamilton Disston, American land developer (d. 1896)
- August 24 – Charles B. Clark, American politician, entrepreneur (d. 1891)
- August 29 – Edward Carpenter, English Socialist poet (d. 1929)
- August 30 – Emily Ruete, princess of Zanzibar (d. 1924)
- September 7 – Charles Romley Alder Wright, British chemist (d. 1894)
- September 13 – Ludwig von Falkenhausen, German general (d. 1936)
- September 16 – Claude-Paul Taffanel, French flutist, composer (d. 1908)
- September 20 – William H. Illingworth, American photographer (d. 1893)
- September 24 – Max Noether, German mathematician (d. 1921)
- September 28 – Robert Stout, 2-time Prime Minister of New Zealand (d. 1930)
- September 29 – Miguel Ángel Juárez Celman, President of Argentina (d. 1909)
- October 5 – Francis William Reitz, 5th State President of the Orange Free State (d. 1934)
- October 11 – Henry J. Heinz, American businessman (d. 1919)
- October 15 – Friedrich Nietzsche, German philosopher (d. 1900)
- October 16 – Ismail Qemali, Albanian civil servant, politician, 1st Prime Minister of Albania (d. 1919)
- October 22 – Louis Riel, Canadian-American leader (d. 1885)
- October 23
- October 24 – Karl Lueger, Vienna, Austria's mayor (d. 1910)
- October 27 – Klas Pontus Arnoldson, Swedish writer, pacifist, recipient of the Nobel Peace Prize (d. 1916)
- November 2 – Mehmed V, Ottoman Sultan (d. 1918)
- November 10 – Henry Eyster Jacobs, American Lutheran theologian (d. 1932)
- November 11 – Marcelino Crisologo, Filipino politician, playwright, writer and poet (d. 1927)
- November 13 – Andrew Harper, Scottish-Australian biblical scholar, teacher (d. 1936)
- November 25 – Karl Benz, German automotive pioneer (d. 1929)
- December 1 – Alexandra of Denmark, queen of Edward VII of England (d. 1925)
- December 8 – Émile Reynaud, French science teacher, animation pioneer (d. 1918)
- December 18 – Takashima Tomonosuke, Japanese general (d. 1916)
- probable – Abdur Rahman Khan, Emir of Kabul, Emir of Kandahar, Emir of Afghanistan (d. 1901)
- Varvara Rudneva, Russian physician (d. 1899)
- January 25 – Jean-Baptiste Drouet, Comte d'Erlon, French marshal (b. 1765)
- January 27 – Charles Nodier, French writer (b. 1780)
- January 29 – Ernest I, Duke of Saxe-Coburg and Gotha (b. 1784)
- February 15 – Henry Addington, 1st Viscount Sidmouth, Prime Minister of the United Kingdom (b. 1757)
- February 27 – Nicholas Biddle, president of the Second Bank of the United States (b. 1786)
- March – Carlota, Cuban slave rebel leader
- March 8 – King Charles XIV John of Sweden, Jean-Baptiste Bernadotte, French Napoleonic general (b. 1763)
- March 20 – Claude Pierre Pajol, French military leader (b. 1772)
- April 3 – Edward Bigge, English cleric, 1st Archdeacon of Lindisfarne (b. 1807)
- April 13 – Mamiya Rinzō, Japanese explorer of Sakhalin (b. 1775)
- April 17 – James Scarlett Abinger, English judge (b. 1769)
- May 18 – Richard McCarty, American politician (b. 1780)
- June 13 – Thomas Charles Hope, Scottish chemist, discoverer of strontium (b. 1766)
- June 15 – Thomas Campbell, Scottish poet (b. 1777)
- June 27
- July 11 – Yevgeny Baratynsky, Russian poet, philosopher (b. 1800)
- July 27 – John Dalton, English chemist, physicist (b. 1766)
- July 28 – Joseph Bonaparte, brother of Napoleon I, King of Naples and Spain (b. 1768)
- July 29 – Franz Xaver Wolfgang Mozart, Austrian composer (b. 1791)
- November 14 – Flora Tristan, French feminist (b. 1803)
- November 29 – Princess Sophia of Gloucester (b. 1773)
- December 2 – Eustachy Erazm Sanguszko, Polish military leader (b. 1768)
- December 24 – Friedrich Bernhard Westphal, Danish-German painter (b. 1803)