The assassination of President 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.

On November 22, 1963, John F. Kennedy, the 35th president of the United States, was assassinated while riding in a presidential motorcade through Dealey Plaza in Dallas, Texas. Kennedy was in the vehicle with his wife, Jacqueline, Texas Governor John Connally, and Connally's wife, Nellie, when he was fatally shot from the nearby Texas School Book Depository by former U.S. Marine Lee Harvey Oswald. The motorcade rushed to Parkland Memorial Hospital, where Kennedy was pronounced dead about 30 minutes after the shooting; Connally was also wounded in the attack but recovered. Vice President Lyndon B. Johnson was hastily sworn in as president two hours and eight minutes later aboard Air Force One at Dallas Love Field.