Which famous writer was Mark Twain's neighbor in Hartford, Connecticut?

Mark Twain's famous writer neighbor in Hartford, Connecticut, was Harriet Beecher Stowe.

Twain and Stowe lived next door to each other in Hartford's Nook Farm neighborhood, a community associated with writers, publishers, and reformers. Stowe was already internationally famous as the author of Uncle Tom's Cabin, her influential 1852 novel about slavery and abolition. Twain moved his family to Hartford in 1871 and later built the house now known as the Mark Twain House, where they lived from 1874.

Stowe's Hartford residence is now the Harriet Beecher Stowe House, also known as the Stowe Center for Literary Activism. The two homes stand adjacent to one another and together form one of the city's best-known literary landmarks. Twain wrote several major works during his Hartford years, including The Adventures of Tom Sawyer, Adventures of Huckleberry Finn, and A Connecticut Yankee in King Arthur's Court.

The question identifies Stowe by her best-known literary achievement, but she was also an abolitionist, essayist, and member of the prominent Beecher family. A frequent error is spelling her name “Harriet Beecher Stow”; the correct form is Harriet Beecher Stowe.