|Covid-19|January 15 – The French newspaper Le Figaro begins publication in Paris, initially as a weekly.
January 30 – The Menai Suspension Bridge, built by engineer Thomas Telford, is opened between the island of Anglesey and the mainland of Wales.
February 8 – Unitarian Bernardino Rivadavia becomes the first President of Argentina.
University College London is founded, under the name University of London.
Swaminarayan writes the Shikshapatri, an important text within Swaminarayan Hinduism.
February 13 – The American Temperance Society is founded.
February 24 – Treaty of Yandabo ends First Anglo-Burmese War, Britain gains Assam, Manipur, Rakhine and Tanintharyi.
March 1 – Chunee the elephant is put to death in London. After arsenic and shooting fail, he is killed with a sword.
March 10 – João VI, King of Portugal and the former Emperor of Brazil, dies after a short illness that had started six day earlier after he had been served dinner while visiting Jerónimos Monastery. An investigative autopsy 174 years later will discover that he had been killed by arsenic poisoning. King João's son, the Emperor Pedro I of Brazil, sails back to Portugal and briefly reigns as King Pedro IV before turning over the Portuguese throne to his daughter, Maria.
April 1 – Samuel Morey patents an internal combustion engine.
April 10 – Third Siege of Missolonghi ends with the massacre of thousands of the Greek defenders by the Ottoman besiegers.
May 28 – Pedro I of Brazil abdicates as King of Portugal.
June – Photography: Nicéphore Niépce makes a true photograph.
June 14–15 – The Auspicious Incident: Mahmud II, sultan of Ottoman Empire, crushes the last mutiny of janissaries in Istanbul.
June 21 – Greek War of Independence: Attempted Ottoman–Egyptian invasion of Mani begins.
June 22 – The Pan-American Congress of Panama tries (unsuccessfully) to unify the republics of the Americas.
Early July – Ludwig van Beethoven puts the finishing touches on the String Quartet in C sharp Minor, Opus 131, the jewel in the crown of his late string quartets.
July 4 – Former US Presidents Thomas Jefferson and John Adams both die on the 50th Anniversary of the signing of the United States Declaration of Independence.
July 26 – The last auto-da-fé is held in Valencia.
August – The town of Crawford Notch suffers a landslide. Those killed include the Willey family, after whom Mount Willey is named.
August 10 – The first Cowes Regatta is held on the Isle of Wight in the UK.
August 18 – Explorer Alexander Gordon Laing becomes the first European to reach Timbuktu.
September 21 – Construction of the Rideau Canal begins in Canada.
October 1 – Opening of the Monkland and Kirkintilloch Railway in Scotland.
October 7 – The first train operates over the Granite Railway in Massachusetts.
November 3 –The Paris Stock Exchange opens at the Palais de la Bourse.
December 21 – Fredonian Rebellion: American settlers in Mexican Texas make the first attempt to secede from Mexico, establishing the Republic of Fredonia, which will survive for just over a month.
The Eggnog Riot breaks out at the United States Military Academy in West Point, New York during the early morning hours, but is squelched by Christmas chapel service.
Major Edmund Lockyer arrives at King George Sound to take possession of the western part of Australia, establishing a settlement near Albany.
The first railway tunnel is built en route between Liverpool and Manchester in England.
The British East India Company colony of the Straits Settlements is established.
Aniline is first isolated from the destructive distillation of indigo by Otto Unverdorben.
Ludwig van Beethoven composes the Große Fuge.
Mahmud II's council orders the janissaries to drill in the European manner.
January 1 – Mikhail Loris-Melikov, Russian statesman and general (d. 1888)
January 12 – William Chapman Ralston, banker and financier (d. 1875)
January 15 – Marie Pasteur, French chemist (d. 1910)
January 26 – Louis Favre, Swiss engineer (d. 1879)
Mikhail Saltykov-Shchedrin, Russian writer (d. 1889)
Richard Taylor, American Confederate general (d. 1879)
January 30 – Robert F. R. Lewis, American naval officer (d. 1881)
February 7 – James Edward Jouett, American admiral (d. 1902)
February 9 – John A. Logan, American soldier and political leader (d. 1886)
February 15 – George Johnstone Stoney, Anglo-Irish physicist (d. 1911)
Hans Peter Jørgen Julius Thomsen, Danish chemist (d. 1909)
Joseph Victor von Scheffel, German poet (d. 1886)
James Calder, 5th President of the Pennsylvania State University
Julia Grant, First Lady of the United States (d. 1902)
John Buford, American general (d. 1863)
Theodore Judah, railroad engineer (d. 1863)
March 24 – Matilda Joslyn Gage, pioneering feminist (d. 1898)
March 29 – Wilhelm Liebknecht, German journalist and politician (d. 1900)
April 3 – Cyrus K. Holliday, cofounder of Topeka, Kansas, and first president of the Atchison, Topeka and Santa Fe Railway (d. 1900)
April 6 – Gustave Moreau, French painter (d. 1898)
April 26 – George Hull Ward, American general (d. 1863)
May 3 – King Charles XV of Sweden and Norway (d. 1872)
May 4 – Frederic Edwin Church, American painter (d. 1900)
May 7 – Varina Davis, First Lady of the Confederate States of America (d. 1906)
May 24 – Marie Goegg-Pouchoulin, Swiss national and international women's rights activist and pacifist (d. 1899)
May 26 – Richard Christopher Carrington, English astronomer (d. 1875)
June 24 – George Goyder, surveyor-general of South Australia (d. 1898)
Stephen Foster, American songwriter and poet (d. 1864)
Green Clay Smith, American temperance movement leader (d. 1895)
July 31 – William S. Clark, American chemist and 3rd President of the Massachusetts Agricultural College
August 7 – Samuel McLean, American congressman (d. 1877)
August 11 – Andrew Jackson Davis, American cobbler (d. 1910)
August 21 – Karl Gegenbaur, German anatomist and professor (d. 1903)
September 8 – Sir James Corry, 1st Baronet, British politician (d. 1891)
September 17 – Bernhard Riemann, German mathematician (d. 1866)
October 8 – Emily Blackwell, American physician (d. 1910)
November 13 – Charles Frederick Worth, English couturier (d. 1895)
November 24 – Carlo Collodi, Italian writer (d. 1890)
November 27 – Jonathan Young, United States Navy commodore (d. 1885)
December 3 – George B. McClellan, American general (d. 1885)
William Daniel (politician), American temperance movement leader (d. 1897)
Cetshwayo kaMpande, Zulu king (d. 1884)
January 3 – Louis-Gabriel Suchet, French marshal (b. 1770)
January 17 – Juan Crisóstomo Arriaga, Spanish composer (b. 1806)
March 29 – Johann Heinrich Voss, German poet (b. 1751)
April 25 – Karl Ludwig von Phull, German military leader (b. 1757)
May 7 – Sophie Hagman, Swedish ballerina and royal mistress (b. 1758)
May 16 – Empress Elizabeth Alexeievna, consort of Alexander I of Russia (b. 1779)
May 16 – Joseph Holt, 1798 United Irish rebel general (b. 1756)
June 3 – Nikolay Karamzin, reformer of the Russian language (b. 1766)
June 5 – Carl Maria von Weber, German composer (b. 1786)
June 7 – Joseph von Fraunhofer, German optician (b. 1787)
John Adams, 2nd President of the United States (b. 1735)
Thomas Jefferson, 3rd President of the United States (b. 1743)
July 5 – Stamford Raffles, British colonial governor and founder of Singapore (b. 1781)
July 8 – Luther Martin, delegate to the American Constitutional Convention (b. 1746)
July 22 – Giuseppe Piazzi, Italian astronomer (b. 1746)
August 13 – René Laennec, French physician (b. 1781)
August 15 – Hanne Tott, Danish circus artist and circus manager (b. 1771)
November 23 – Johann Elert Bode, German astronomer (b. 1747)
December 11 – Queen-Empress Maria Leopoldina, consort of Pedro IV of Portugal & I of Brazil (b. 1797)
1826 (MDCCCXXVI) was a common year starting on Sunday (dominical letter A) of the Gregorian calendar and a common year starting on Friday (dominical letter C) of the Julian calendar, the 1826th year of the Common Era (CE) and Anno Domini (AD) designations, the 826th year of the 2nd millennium, the 26th year of the 19th century, and the 7th year of the 1820s decade. As of the start of 1826, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.