JFK asassination
The grand-daddy of conspiracy theories. US President John Fitzgerald 'Jack' Kennedy was shot in Dallas on 22nd Nov 1963 and the official 'Warren Report' into his death pinned the blame totally on Lee Harvey Oswald as being the sole culprit. Several other investigations done by Dallas Police, the FBI and other government bodies throughout the years have similarly concluded this fact.
Despite this the murder has been the subject of numerous books, movies and articles all with different theories as to what happened, but all essentially refuting the "official version of events". Oswald’s links to Russia along with the fact that Oswald was shot very soon after by a small-time crook with Mafia connections opened lots of avenues for speculation.
The murder has led to several terms closely associated with conspiracies: terms such as 'grassy knoll', 'second shooter' and 'magic bullet' have all entered common parlance.