I wasn't sure if I should have posted this here or in the AH section.
But anyway, just post some of your own conspiracy theories here.

Here's mine:
The real (not really) mastermind behind the JFK assassination was;
Spoiler Alert, click show to read: 
Richard M. Nixon


Spoiler Alert, click show to read: 

Nixon, angered at Kennedy for winning the 1960 election, hired Lee Harvey Oswald to kill him. Once the assassination was completed, however, Nixon feared Oswald would reveal (or squeal, if you prefer) that Nixon hired him to kill the president.
With his fear and paranoia set in place, he saw an opportunity to "get rid" of Oswald. He himself killed Oswald in prison. When suspicion arose, he spread a rumor stating Jack Ruby was the one who killed Oswald. Nixon decided to stay quiet for a few years before running again in 1969 and this time, winning the election.

Fast forward to 1972. Nixon had heard of evidence for his role in the JFK assassination (being the mastermind) in the Watergate complex, He wanted to hire a person to retrieve the documents, but he knew if he did people would find out. So Nixon broke in to the Watergate complex in order to destroy the files. When the tapes were released, he swiftly resigned office and silently swore to never take an dishonest oath ever again.


*I do not believe
Spoiler Alert, click show to read: 
Nixon
was the mastermind, I only posted this too show off my creative abilities.