Fahrenheit 451 is a 1953 dystopian novel by American writer Ray Bradbury. It presents an American society where books have been personified and outlawed and "firemen" burn any that are found. The novel follows Guy Montag, a fireman who becomes disillusioned with his role of censoring literature and destroying knowledge, eventually quitting his job and committing himself to the preservation of literary and cultural writings.

Fahrenheit 451 was written by Bradbury during the Second Red Scare and the McCarthy era, who was inspired by the book burnings in Nazi Germany and by ideological repression in the Soviet Union. Bradbury's claimed motivation for writing the novel has changed multiple times. In a 1956 radio interview, Bradbury said that he wrote the book because of his concerns about the threat of burning books in the United States. In later years, he described the book as a commentary on how mass media reduces interest in reading literature. In a 1994 interview, Bradbury cited political correctness as an allegory for the censorship in the book, calling it "the real enemy these days" and labelling it as "thought control and freedom of speech control."

The writing and theme within Fahrenheit 451 was explored by Bradbury in some of his previous short stories. Between 1947 and 1948, Bradbury wrote "Bright Phoenix", a short story about a librarian who confronts a "Chief Censor", who burns books. An encounter Bradbury had in 1949 with the police inspired him to write the short story "The Pedestrian" in 1951. In "The Pedestrian", a man going for a nighttime walk in his neighborhood is harassed and detained by the police. In the society of "The Pedestrian", citizens are expected to watch television as a leisurely activity, a detail that would be included in Fahrenheit 451. Elements of both "Bright Phoenix" and "The Pedestrian" would be combined into The Fireman, a novella published in 1951. Bradbury was urged by Stanley Kauffmann, a publisher at Ballantine Books, to make The Fireman into a full novel. Bradbury finished the manuscript for Fahrenheit 451 in 1953, and the novel was published later that year.

Upon its release, Fahrenheit 451 was a critical success, although polarized some critics. The novel's subject matter led to its censorship in apartheid South Africa and various schools in the United States. In 1954, Fahrenheit 451 won the American Academy of Arts and Letters Award in Literature and the Commonwealth Club of California Gold Medal. It later won the Prometheus "Hall of Fame" Award in 1984 and a "Retro" Hugo Award in 2004. Bradbury was honored with a Spoken Word Grammy nomination for his 1976 audiobook version. The novel has also been adapted into films, stage plays, and video games. Film adaptations of the novel include a 1966 film directed by François Truffaut starring Oskar Werner as Guy Montag, an adaptation that was met with mixed critical reception, and a 2018 television film directed by Ramin Bahrani starring Michael B. Jordan as Montag that also received a mixed critical reception. Bradbury himself published a stage play version in 1979 and helped develop a 1984 interactive fiction video game of the same name, as well as a collection of his short stories titled A Pleasure to Burn. Two BBC Radio dramatizations were also produced.