Space aliens. The Federal Reserve. The Freemasons. Zionist bankers. The Vatican. The British crown. 
Space aliens. The Federal Reserve. The Freemasons. Zionist bankers. The Vatican. The British crown. The Israeli government. The military-industrial complex. Ngo Dinh Diem. Texas oilmen. The CIA. The KGB. The FBI. The Mafia. Right-wing Cuban exiles. Left-wing Castro followers. Mac Wallace. Aristotle Onassis and the Illuminati. Lyndon Johnson. Himself. For ten points, these people and others have all been blamed for what event, generally ascribed to Lee Harvey Oswald?
Space aliens. The Federal Reserve. The Freemasons. Zionist bankers.
{Assassination of JFK} [accept equivalents]