Possibly the most famous presidential scandal, JFK and Marilyn Monroe’s affair has never actually been proven. The two did meet on several occasions, and there are reports that he once asked her to go on vacation with him alone. Beyond that, there are only rumors. It’s been said that after Jack Kennedy tired of her, she took up with his younger (and more devoutly Catholic) brother, Robert. Her last public appearance was the infamous Happy Birthday incident in 1962. Author Norman Mailer eventually asserted that he believed the CIA murdered Monroe because of the scandal.