The assassination of John F. Kennedy on November 22, 1963, has spawned numerous conspiracy theories. These theories allege the involvement of the CIA, the Mafia, Vice President Lyndon B. Johnson, Cuban Prime Minister Fidel Castro, the KGB, or some combination of these individuals and entities. Some conspiracy theories have alleged a coverup by parts of the federal government, such as the original FBI investigators, the Warren Commission, or the CIA. Former Los Angeles District Attorney Vincent Bugliosi estimated that a total of 42 groups, 82 assassins, and 214 people had been accused at one time or another in various conspiracy scenarios.
The number of books written about the assassination of Kennedy has been estimated to be between 1,000 and 2,000. According to Bugliosi, 95% of those books are "pro-conspiracy and anti-Warren Commission". Very few of the books and articles published about the assassination have been written by historians. Calvin Trillin's article, "The Buffs" in the June 1967 edition of The New Yorker, has been credited as the first addressing the "conspiracy phenomenon".