|Centuries:||18th century – 19th century – 20th century|
|Decades:||1780s 1790s 1800s – 1810s – 1820s 1830s 1840s|
|Years:||1815 1816 1817 – 1818 – 1819 1820 1821|
Year 1818 (MDCCCXVIII) was a common year starting on Thursday (link will display the full calendar) of the Gregorian Calendar (or a common year starting on Tuesday of the 12-day slower Julian calendar).
Events of 1818
January - June
- January 1 - - Mary Shelley's Frankenstein is published.
- January 3 - At 21:52 UTC, Venus occulted Jupiter. It was the last occultation of a planet by another planet before November 22, 2065.
- February 12 - Chile proclaims its independence from Spain.
- March 22 - Easter Sunday in Western Christianity falls on its earliest possible date in this year. Easter in Western Christianity will not occur on this date again until 2285.
- April 4 - The U.S. Congress adopts the flag of the United States as having 13 red and white stripes and one star for each state (20 stars) with additional stars to be added whenever a new state is added to the Union.
- April 7 - Brooks Brothers, the oldest men's clothier in the United States, opens its first store on the Northeast corner of Catherine and Cherry Streets in New York City, where the South Street Seaport now stands.
- May 11 - Charles XIV of Sweden-Norway is crowned king of Sweden.
July - December
- September 7 - Carl III of Sweden-Norway is crowned king of Norway, in Trondheim.
- September 23 - Formal installation of border markers for the European territory of Moresnet.
- October 20 - A convention between the U.S. and the United Kingdom establishes the northern boundary as the forty-ninth parallel from the Lake of the Woods to the Rocky Mountains, also creating the Northwest Angle.
- November 11 - Anglo-Chinese College founded by Robert Morrison in Malacca.
- December 3 - Illinois is admitted as the 21st U.S. state.
- December 24 - " Silent Night" composed by Franz Xaver Gruber and Josef Mohr.
- Lord Hastings, governor-general of India, gives approval to Sir Stamford Raffles to establish trading station at the southern tip of the Malay Peninsula (modern-day Singapore).
- Andrew Jackson invades Florida.
- Third Anglo-Maratha War ends, resulting in the breakup of the Maratha Empire and the loss of Maratha independence to the British.
|Ab urbe condita||2571|
|British Regnal year||58 Geo. 3 – 59 Geo. 3|
|Chinese calendar|| 丁丑年十一月廿五日
— to —戊寅年十二月初五日
|- Vikram Samvat||1874–1875|
|- Shaka Samvat||1740–1741|
|- Kali Yuga||4919–4920|
|- Ǹrí Ìgbò||818–819|
|Japanese calendar|| Bunka 15 Bunsei 1
|Juche calendar||N/A (before 1912)|
|Julian calendar||Gregorian minus 12 days|
|Minguo calendar||94 before ROC
|Thai solar calendar||2361|
January - June
- January 30 - Artúr Görgey, Hungarian military general and politician (d. 1916)
- February 14 - Frederick Douglass, (His day of birth was never established; he adopted this date.) American abolitionist author and statesman (d. 1895)
- March 22 - John Ainsworth Horrocks, English-born explorer of South Australia (d. 1846)
- April 4 - Thomas Mayne Reid, Irish-American novelist (d. 1883)
- April 8 - King Christian IX of Denmark (d. 1906)
- April 17 - Emperor Alexander II of Russia (d. 1881)
- May 5 - Karl Marx, German political philosopher (d. 1883)
- June 17
- June 18 - Angelo Secchi, Italian astronomer (d. 1878)
July - December
- July 18 - Celadon Leeds Daboll, American merchant and inventor (d. 1866)
- July 22 - J. Gregory Smith, Vermont governor (d. 1891)
- July 30 - Emily Brontë, British novelist (d. 1848)
- September 27 - Adolph Wilhelm Hermann Kolbe, German chemist (d. 1884)
- October 8 - John Henninger Reagan, American Confederate politician (d. 1905)
- October 18 - Edward Ord, U.S. Army officer (d. 1883)
- November 9 ( October 28 (O.S.)) - Ivan Turgenev, Russian writer (d. 1883)
- November 29 - George Brown, Canadian politician (d. 1880)
- December 13 - Mary Todd Lincoln, First Lady of the United States (d. 1882)
- December 24 - James Prescott Joule, British physicist (d. 1889)
- January 11 - Johann David Wyss, Swiss author (b. 1743)
- February 5 - Charles XIII/Charles II, King of Sweden and Norway (b. 1748)
- February 13 - George Rogers Clark, American Revolutionary leader
- February 15 - Friedrich Ludwig, Fürst zu Hohenlohe-Ingelfingen, Prussian general (b. 1746)
- May 10 - Paul Revere, American patriot and silversmith (b. 1735)
- June 12 - Egwale Seyon, Emperor of Ethiopia.
- September 1 - Robert Calder, British naval officer (b. 1745)
- October 28 - Abigail Adams, First Lady of the United States (b. 1744)
- October 28 - Henri Jacques Guillaume Clarke, duc de Feltre, French marshal and politician (b. 1765)
- November 17 - Charlotte of Mecklenburg-Strelitz, queen of George III of the United Kingdom (b. 1744)
- December 25 - Dominique Catherine de Pérignon, Marshal of France (b. 1754)