The American writer best known for his novel "The Adventures of Huckleberry Finn" is Mark Twain. This iconic work, published in 1884, is celebrated for its vivid portrayal of pre-Civil War America and its exploration of themes such as race, freedom, and morality. Twain's use of regional dialects and unique narrative style offers readers a deep insight into the social issues of his time, making the novel a cornerstone of American literature and a critical commentary on the societal attitudes of the era.