1841 (MDCCCXLI) was a common year starting on Friday of the Gregorian calendar and a common year starting on Wednesday of the Julian calendar, the 1841st year of the Common Era (CE) and Anno Domini (AD) designations, the 841st year of the 2nd millennium, the 41st year of the 19th century, and the 2nd year of the 1840s decade. As of the start of 1841, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.
January 20 – Charles Elliot of the United Kingdom and Qishan of the Qing dynasty agree to the Convention of Chuenpi.
January 26 – Britain occupies Hong Kong. Later in the year, the first census of the island records a population of about 7,500.
January 27 – The active volcano Mount Erebus in Antarctica is discovered, and named by James Clark Ross.
January 28 – Ross discovers the "Victoria Barrier", later known as the Ross Ice Shelf. On the same voyage, he discovers the Ross Sea, Victoria Land and Mount Terror.
El Salvador proclaims itself an independent republic, bringing an end to the Federal Republic of Central America.
A fire destroys two-thirds of the city of Mayagüez, Puerto Rico.
February 4 – The first known reference is made to Groundhog Day, celebrated in North America, in the diary of a James Morris.
February 10 – The Act of Union (British North America Act, 1840) is proclaimed in Canada.
February 11 – Upper Canada and Lower Canada are merged to create the United Province of Canada.
February 18 – The first ongoing filibuster in the United States Senate begins, and lasts until March 11.
March 9 – United States v. The Amistad: The Supreme Court of the United States rules in the case, that the Africans who seized control of the ship had been taken into slavery illegally.
March 12 – All 136 passengers and crew on steamship SS President, commanded by legendary captain Richard Roberts (known for saying "I'd go to sea in a bathtub"), are killed when the ship founders in rough seas.
April 4 – President William Henry Harrison dies of pneumonia, aged 68, becoming the first president of the United States to die in office, and at one month, the American president with the shortest term served. He is succeeded by Vice President John Tyler.
May – The Sino-Sikh War begins.
May 3 – New Zealand becomes a separate British colony, having previously been administered as part of the Colony of New South Wales.
May 22 – The Georgian province of Guria revolts against the Russian Empire.
June 6 – The United Kingdom Census is held, the first to record names and approximate ages of every household member, and to be administered nationally.