All the King's Men is a 1946 novel by Robert Penn Warren. Its title is drawn from the nursery rhyme "Humpty Dumpty". The novel tells the story of charismatic populist governor Willie Stark and his political machinations in the Depression-era Deep South. It is commonly thought to have been loosely inspired by the real-life story of U.S. Senator Huey P. Long, who was assassinated in 1935.

Warren won the Pulitzer Prize for All the King's Men in 1947. The novel has received critical acclaim and remained perennially popular since its first publication. It was rated the 36th greatest novel of the 20th century by Modern Library, and it was chosen as one of Time magazine's 100 best novels since 1923.

All the King's Men portrays the dramatic and theatrical political rise and governorship of Willie Stark, a cynical populist in the 1930s American South.