3. Marilyn Monroe: Porn Star/President Lover
The Rumour: Not only was Marilyn Monroe having an affair with JFK - as proved by the sexual tension in the infamous "Happy Birthday, Mr President" affair - she also starred in an adult movie, discovered by a Swedish photographer in 1980 (as reported by Penthouse magazine.) Said film can now be seen online in several places, after it re-emerged in 1997 thanks to Spanish film collector Mikel Barsa.
The Truth: The porn film appears to be a fake - unless you suspend all logic, squint your eyes extremely tight and ignore almost everything we know about Monroe. Not only does the timeline not fit with Monroe's rise to fame (she would have been younger than 21 when it was filmed, and the star is clearly in her thirties at least), there is little suggestion Monroe would have done anything more erotic after the infamous shoot with Tom Kelley (which was suggested as simply a response to needing to pay her rent). The woman in the film also bears very little resemblance to Monroe, and though it is suggested as a pre-groomed version of her, before Hollywood sculpted her into a star, it's still too much of a stretch. And as for the Presidential affair, it all depends on who you listen to, but there is certainly some pressing evidence, such as the accounts of those who new JFk closely like Philip Watson, a former Los Angeles county assessor, who met Monroe while she was with Kennedy at Bing Crosby's house:
"There was no question in my mind that Marilyn and the President were together. They were having a good time. She'd had a lot to drink. It was obvious they were intimate and that they were staying there together for the night."
The legend of JFk certainly seems to suggest it was a possibility - definitely more than the adult movie story anyway.