Mark TWAIN, also known as Samuel Clemens, is the creator of the classic novel Tom Sawyer. He was an American author and humorist who wrote during the 19th century. His real name was Samuel Langhorne Clemens, but he adopted the pen name Mark TWAIN, which is derived from a phrase used by riverboat workers meaning 'two fathoms deep.' TWAIN is best known for his novels The Adventures of Tom Sawyer and its sequel, Adventures of Huckleberry Finn.