1855 was a common year.
|Centuries:||18th century – 19th century – 20th century|
|Decades:||1820s 1830s 1840s – 1850s – 1860s 1870s 1880s|
|Years:||1852 1853 1854 – 1855 – 1856 1857 1858|
- January 1 – London, Ontario is incorporated as a city.
- January 23 – The first bridge over the Mississippi River opens in what is now Minneapolis, Minnesota, a crossing made today by the Father Louis Hennepin Bridge.
- January 23 – The region of Wairarapa, New Zealand was hit by the strongest earthquake ever recorded in New Zealand, which reached Magnitude 8.1 on the Richter Scale. There were five deaths.
- January 29 – Lord Aberdeen resigns as Prime Minister of the United Kingdom over the management of the Crimean War.
- February 5 – Lord Palmerston becomes Prime Minister of the United Kingdom
- February 11 – Kassa Hailu is crowned Tewodros II, Emperor of Ethiopia, by Abuna Salama III in a ceremony at the church of Derasge Maryam.
- March 3 – US Congress appropriates $30,000 to create US Camel Corps
- March 16 – Bates College in Lewiston, Maine was founded.
- May 15 – The Great Gold Robbery of 1855 in England
- June 29 – The Daily Telegraph begins publication
- September 3 – Last Bartholomew Fair on London, England
- September 11 – Sevastapol falls to the British troops
- December 22 – Metropolitan Board of Works established.
- Stamp duty was removed from newspapers in Britain creating mass market media in the UK.
- The Panama Railway becomes the first railroad to connect the Atlantic Ocean and Pacific Ocean by rail as the railroad's route across Panama is completed.