Napoleon Hill (1883-1970) was an American author, lecturer, and self-help guru known for his works on personal development and success. He is best known for his book "Think and Grow Rich", which has sold over 100 million copies worldwide and has influenced many successful people. Hill started his career as a journalist and later became an advisor to prominent businessmen and politicians. He devoted much of his life to researching and writing about success, and his work has had a significant impact on the self-help genre.