20 Things You Didn't Know About JFK
8. X Is Not Entirely A Fictitious Character
Halfway through the film, Garrison meets with a man simply known as X (Donald Sutherland) who gives a breathless monologue about behind-the-scenes actions taking place leading up to the assassination that implicated everyone from Bell Helicopter - who stood to profit from the Vietnam invasion - and several top generals and LBJ himself.
Most assumed X was some kind of composite character meant to tie together numerous threads to cohere, however, they were mistaken. X is primarily based on Fletcher Prouty, a retired Air Force Colonel who, while he didn't meet with Garrison in person, but served as a technical adviser to the film and who stone described meeting as "one of the most extraordinary afternoons I've ever spent. Pretty much like in the movie, he just started to talk."