Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), known by his pen name Mark Twain, was an American author and humorist. He is noted for his novels Adventures of Huckleberry Finn (1885), called "the Great American Novel", and The Adventures of Tom Sawyer (1876). Twain was a friend to presidents, artists, industrialists, and European royalty.

Twain was popular, and his wit and satire earned praise from critics and peers. Upon his death he was lauded as the "greatest American humorist of his age", and William Faulkner called Twain "the father of American literature".

Samuel Langhorne Clemens was born in Florida, Missouri, on November 30, 1835, to a Tennessee country merchant, John Marshall Clemens (August 11, 1798 – March 24, 1847), and Jane Lampton Clemens (June 18, 1803 – October 27, 1890). John Marshall Clemens was the first of five children born to Samuel B Clemens and Pamela Goggin (1775 – 1844), who married on October 29, 1797 in Bedford County, Virginia.

Twain was the sixth of seven children. Only three siblings survived childhood: his brother Orion (July 17, 1825 – December 11, 1897); Henry, who died in a riverboat explosion (July 13, 1838 – June 21, 1858); and Pamela (September 19, 1827 – August 31, 1904). His sister Margaret (May 31, 1830 – August 17, 1839) died when Twain was three, and his brother Benjamin (June 8, 1832 – May 12, 1842) died three years later. Another brother, Pleasant (1828 – 1829), died at six months. Twain was born two weeks after the closest approach to Earth of Halley's Comet. On December 4, 1985, the United States Postal Service issued a stamped envelope for "Mark Twain and Halley's Comet."

When Twain was four, his family moved to Hannibal, Missouri, a port town on the Mississippi River that inspired the fictional town of St. Petersburg in The Adventures of Tom Sawyer and Adventures of Huckleberry Finn. Missouri was a slave state and young Twain became familiar with the institution of slavery, a theme he would later explore in his writing.

Twain’s father was an attorney and a local judge. The Hannibal and St. Joseph Railroad was organized in his office in 1846. The railroad connected the second and third largest cities in the state and was the westernmost United States railroad until the Transcontinental Railroad. It delivered mail to and from the Pony Express.

In March 1847, when Twain was 11, his father died of pneumonia. The next year, he became a printer's apprentice. In 1851, he began working as a typesetter and contributor of articles and humorous sketches for the Hannibal Journal, a newspaper owned by his brother Orion. When he was 18, he left Hannibal and worked as a printer in New York City, Philadelphia, St. Louis, and Cincinnati. He joined the union and educated himself in public libraries in the evenings, finding wider information than at a conventional school. At 22, Twain returned to Missouri.

On a voyage to New Orleans down the Mississippi, the steamboat pilot, Horace E. Bixby, inspired Twain to be a steamboat pilot. As Twain observed in Life on the Mississippi, the pilot surpassed a steamboat's captain in prestige and authority; it was a rewarding occupation with wages set at $250 per month, roughly equivalent to $72,400 a year today. A steamboat pilot needed to know the ever changing river to be able to stop at the hundreds of ports and wood lots. Twain studied 2,000 miles (3,200 km) of the Mississippi for more than two years before he received his steamboat pilot license in 1859.

While training, Samuel convinced his younger brother Henry to work with him. Henry was killed on June 21, 1858, when the steamboat on which he was working, the Pennsylvania, exploded. Twain had foreseen this death in a dream a month earlier, which inspired his interest in parapsychology; he was an early member of the Society for Psychical Research. Twain was guilt stricken and held himself responsible for the rest of his life. He continued to work on the river and was a river pilot until the American Civil War broke out in 1861 and traffic along the Mississippi was curtailed.

Missouri was considered by many to be part of the South, and was represented in both the Confederate and Federal governments during the Civil War. Twain wrote a sketch, "The Private History of a Campaign That Failed", which claimed he and his friends had been Confederate volunteers for two weeks before disbanding their company.

Twain joined Orion, who in 1861 became secretary to James W. Nye, the governor of Nevada Territory, and headed west. Twain and his brother traveled more than two weeks on a stagecoach across the Great Plains and the Rocky Mountains, visiting the Mormon community in Salt Lake City. The experiences inspired Roughing It and provided material for The Celebrated Jumping Frog of Calaveras County. Twain's journey ended in the silver mining town of Virginia City, Nevada, where he became a miner. Twain failed as a miner and worked at a Virginia City newspaper, the Territorial Enterprise. Here he first used his pen name. On February 3, 1863, he signed a humorous travel account "Letter From Carson – re: Joe Goodman; party at Gov. Johnson's; music" with "Mark Twain".

Twain moved to San Francisco, California in 1864, still as a journalist. He met writers such as Bret Harte, Artemus Ward, and Dan DeQuille. The young poet Ina Coolbrith may have romanced him.

His first success as a writer came when his humorous tall tale, "The Celebrated Jumping Frog of Calaveras County", was published in a New York weekly, The Saturday Press, on November 18, 1865. It brought him national attention. A year later, he traveled to the Sandwich Islands (present day Hawaii) as a reporter for the Sacramento Union. His travelogues were popular and became the basis for his first lectures.

In 1867, a local newspaper funded a trip to the Mediterranean. During his tour of Europe and the Middle East, he wrote a popular collection of travel letters, which were later compiled as The Innocents Abroad in 1869. It was on this trip that he met his future brother - in - law.

Charles Langdon showed a picture of his sister, Olivia, to Twain; Twain claimed to have fallen in love at first sight. The two met in 1868, were engaged a year later, and married in February 1870 in Elmira, New York. She came from a "wealthy but liberal family", and through her he met abolitionists, "socialists, principled atheists and activists for women's rights and social equality", including Harriet Beecher Stowe (his next door neighbor in Hartford, Connecticut), Frederick Douglass, and the writer and utopian socialist William Dean Howells, who became a longtime friend.

The couple lived in Buffalo, New York from 1869 to 1871. Twain owned a stake in the Buffalo Express newspaper, and worked as an editor and writer. Their son Langdon died of diphtheria at 19 months.

In 1871, Twain moved his family to Hartford, Connecticut, where starting in 1873, he arranged the building of a home (local admirers saved it from demolition in 1927 and eventually turned it into a museum focused on him). While living there Olivia gave birth to three daughters: Susy (1872 – 1896), Clara (1874 – 1962) and Jean (1880 – 1909). The couple's marriage lasted 34 years, until Olivia's death in 1904.

During his seventeen years in Hartford (1874 – 1891), Twain wrote many of his best known works: The Adventures of Tom Sawyer (1876), The Prince and the Pauper (1881), Life on the Mississippi (1883), Adventures of Huckleberry Finn (1884), and A Connecticut Yankee in King Arthur's Court (1889).

Twain made a second tour of Europe, described in the 1880 book A Tramp Abroad. His tour included a stay in Heidelberg from May 6 until July 23, 1878, and a visit to London.

He was fascinated with science and scientific inquiry. He developed a close and lasting friendship with Nikola Tesla, and the two spent much time together in Tesla's laboratory.

Twain patented three inventions, including an "Improvement in Adjustable and Detachable Straps for Garments" (to replace suspenders) and a history trivia game. Most commercially successful was a self - pasting scrapbook; a dried adhesive on the pages only needed to be moistened before use.

His book A Connecticut Yankee in King Arthur's Court features a time traveler from contemporary America, using his knowledge of science to introduce modern technology to Arthurian England. This type of storyline would later become a common feature of the science fiction sub - genre, Alternate history.

In 1909, Thomas Edison visited Twain at his home in Redding, Connecticut, and filmed him. Part of the footage was used in The Prince and the Pauper (1909), a two - reel short film.

Twain made a substantial amount of money through his writing, but he squandered much of it in bad investments, mostly in new inventions, particularly the Paige typesetting machine. It was a beautifully engineered mechanical marvel that amazed viewers when it worked, but was prone to breakdowns. Twain spent $300,000 (equal to $7,518,462 today) on it between 1880 and 1894, but before it could be perfected, it was made obsolete by the Linotype. He lost not only the bulk of his book profits but also a large portion of the inheritance of his wife.

Twain also lost money through his publishing house, which enjoyed initial success selling the memoirs of Ulysses S. Grant, but went broke soon after, losing money on a biography of Pope Leo XIII; fewer than two hundred copies were sold.

Twain's writings and lectures, combined with the help of a new friend, enabled him to recover financially. In 1893, he began a 15 year long friendship with financier Henry Huttleston Rogers, a principal of Standard Oil. Rogers first made Twain file for bankruptcy. Then Rogers had Twain transfer the copyrights on his written works to his wife, Olivia, to prevent creditors from gaining possession of them. Finally, Rogers took absolute charge of Twain's money until all the creditors were paid.

Twain embarked on an around - the - world lecture tour in 1894 to pay off his creditors in full, although he was no longer under any legal obligation to do so. In mid 1900, he was the guest of newspaper proprietor Hugh Gilzean - Reid at Dollis Hill House. Twain wrote of Dollis Hill that he had "never seen any place that was so satisfactorily situated, with its noble trees and stretch of country, and everything that went to make life delightful, and all within a biscuit's throw of the metropolis of the world". He returned to America in 1900, having earned enough to pay off his debts.

Twain was in demand as a featured speaker, and appeared before many men's clubs, including the White Friars, the Vagabonds, the Authors, the Monday Evening Club of Hartford, and the Beefsteak Club. He was made an honorary member of the Bohemian Club in San Francisco. In the late 1890s, he spoke to the Savage Club in London and was elected honorary member. When told that only three men had been so honored, including the Prince of Wales, he replied "Well, it must make the Prince feel mighty fine." In 1897, Twain spoke to the Concordia Press Club in Vienna as a special guest, following diplomat Charlemagne Tower. In German, to the great amusement of the assemblage, Twain delivered the speech "Die Schrecken der deutschen Sprache" ("The Horrors of the German Language").

Twain passed through a period of deep depression, which began in 1896 when his daughter Susy died of meningitis. Olivia's death in 1904 and Jean's on December 24, 1909, deepened his gloom. On May 20, 1909, his close friend Henry Rogers died suddenly.

In 1906, Twain began his autobiography in the North American Review. In April, Twain heard that his friend Ina Coolbrith had lost nearly all she owned in the 1906 San Francisco earthquake, and he volunteered a few autographed portrait photographs to be sold for her benefit. To further aid Coolbrith, George Wharton James visited Twain in New York and arranged for a new portrait session. Twain said four of the resulting images were the finest ones ever taken of him.

Twain formed a club in 1906 for girls he viewed as surrogate granddaughters, the Angel Fish and Aquarium Club. The dozen or so members ranged in age from 10 to 16. Twain exchanged letters with his "Angel Fish" girls and invited them to concerts and the theater and to play games. Twain wrote in 1908 that the club was his "life's chief delight."

Oxford University awarded Twain an honorary doctorate in letters (D.Litt.) in 1907.

In 1909, Twain is quoted as saying:

I came in with Halley's Comet in 1835. It is coming again next year, and I expect to go out with it. It will be the greatest disappointment of my life if I don't go out with Halley's Comet. The Almighty has said, no doubt: 'Now here are these two unaccountable freaks; they came in together, they must go out together.'

His prediction was accurate – Twain died of a heart attack on April 21, 1910, in Redding, Connecticut, one day after the comet's closest approach to Earth.

Upon hearing of Twain's death, President William Howard Taft said:

"Mark Twain gave pleasure – real intellectual enjoyment – to millions, and his works will continue to give such pleasure to millions yet to come... His humor was American, but he was nearly as much appreciated by Englishmen and people of other countries as by his own countrymen. He has made an enduring part of American literature."

Twain's funeral was at the "Old Brick" Presbyterian Church in New York. He is buried in his wife's family plot at Woodlawn Cemetery in Elmira, New York. His grave is marked by a 12 foot (i.e., two fathoms, or "mark twain") monument, placed there by his surviving daughter, Clara. There is also a smaller headstone.