Who killed John F. Kennedy?

Despite the conspiracy theories surrounding the Kennedy case, it has been determined by the Warren Commission that Lee Harvey Oswald killed John F. Kennedy on November 22, 1963.
John F. Kennedy had made a great deal of enemies during his short time in office. Southern Democrats did not like him for his stance favoring integration. Organized crime did not like him since the president's brother, Robert Kennedy, was the attorney general and was quite tough on crime. Fidel Castro did not like Kennedy because of his attempts to assassinate him. Some in the Soviet Union did not like Kennedy for his hard stance during the Cuban Missile Crisis.
Despite this long list of potential enemies, in 1964 the Warren Commission determined that Oswald acted alone in killing Kennedy. Despite recent investigations into other theories and the recent opening of the Kennedy papers, there has not been enough evidence to change this conclusion.