1838 (MDCCCXXXVIII) was a common year starting on Monday of the Gregorian calendar and a common year starting on Saturday of the Julian calendar, the 1838th year of the Common Era (CE) and Anno Domini (AD) designations, the 838th year of the 2nd millennium, the 38th year of the 19th century, and the 9th year of the 1830s decade. As of the start of 1838, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.

• January 10 – a fire destroys Lloyd's Coffee House and the Royal Exchange in London.
• April 30 – Nicaragua declares independence from the Central American Federation (See Nicaragua's early history)
• May – The People's Charter drawn up in the United Kingdom demanding universal suffrage.
• May 26 – USA: Trail of Tears – forced relocation of the Cherokee tribe, killing at least 8,000.
• 1 August – Trinidad and Tobago: Slavery officially abolished
• 7 September – The paddlesteamer Forfarshire foundered on the Farne Islands, UK, giving rise to the fame of Grace Darling, who rescued nine passengers.
• November 3 India: The Bombay Times and Journal of Commerce is founded. This paper was later renamed to The Times of India in 1861
• November 5 – Central American Civil War begins with Honduras' separation from the Central American Federation.
• December – Beginning of Pastry War: Mexico invaded by French forces

• January 4 – General Tom Thumb, American circus performer and entertainer (d. 1883)
• January 6 – Max Bruch, German composer (d. 1920)
• January 16 – Franz Brentano, German philosopher and psychologist (d. 1917)
• February 6 – Henry Irving, English actor (d. 1905)
• February 10 – Gustav Oelwein, founder of Oelwein, Iowa (d. 1913)
• February 18 – Ernst Mach, Austrian physicist and philosopher
• March 3 – George William Hill, American astronomer
• April 3 – John Willis Menard, African-American politician
• April 8 – Ferdinand von Zeppelin, German inventor
• April 12 – John Shaw Billings, M.D., American military and medical leader
• April 16 – Martha McClellan Brown, American temperance movement leader
• May 10 – John Wilkes Booth, the man who killed United States President Abraham Lincoln.
• May 20 – Jules Méline, French statesman
• September 23 - Victoria Woodhull - the first woman to be up for candidate for the President of the United States.
• September 28 – Sai Baba of Shirdi, Indian national saint (d. 1918)
• November 29 – Giovanni Losi, Italian Combonian catholic missionary (d. 1882)

• January 3 – Prince Maximilian of Saxony
• January 5 – Anthony Van Egmond, rebel leader in Upper Canada Rebellion of 1837 {died in jail}
• February 21 – Silvestre de Sacy, linguist
• March 13 – Poul Martin Møller, philosopher
• April 9 – Piet Uys, Voortrekker leader (in battle)
• May 17 – Charles Maurice de Talleyrand, French diplomat
• July 19 – Christmas Evans, preacher
• August 17 – Lorenzo Da Ponte, librettist for Mozart
• August 21 – Adelbert von Chamisso, German writer
• September 1 – William Clark, American explorer
• October 1 – Charles Tennant, Scottish chemist and industrialist
• November 21 – Georges Mouton, count of Lobau, Marshal of France