13. John F. Kennedy was assassinated over the Federal Reserve.
12. Baseball player Joe DiMaggio did it.
11. The "three tramps" theory.
10. The driver did it.
9. The "umbrella man" theory.
The theory: Louie Steven Witt, who appears in the Zapruder film, used a black umbrella to signal either shooters planted in the book depository or the grassy knoll to orchestrate the assassination. Or, in more imaginative versions, he shot a poison dart concealed within the umbrella. The filmmaker Errol Morris also explored this theory in a mini-documentary for The New York Times.
How likely is it? Even though he's been mentioned in Oliver Stone's JFK and The X-Files, Witt has said that he really had the umbrella to taunt JFK because he didn't like the Kennedy family's Nazi ties from World War II.
8. It was all organized by Lyndon B. Johnson.
7. The "friendly fire" theory.
6. It was organized by the Soviet Union.
The theory: Soviet Union Leader Nikita Khrushchev (right) organized the assassination, using Communist sympathizer Lee Harvey Oswald, to retaliate for the Cuban Missile Crisis.
How likely is it? In 1966, Col. Boris Ivanov, chief of the KGB, actually told the FBI that he thought the assassination was planned by a group, but not by the Soviets. When the FBI spoke to members of the Soviet Union, they were apparently under the impression that JFK's death was part of a coup by the ultra-right. A book was written by a high-ranking Soviet Bloc defector maintaining that the KGB was definitely involved, though.