However, not only was he an acclaimed film director, he was also an incredibly interesting man with a wealth of rich quotes on film, life and even his ability to connect with people via the media of stress.
While he admitted he still loved old films, he recently revealed what his favourite scary movie was - and it is as recent as could be!
Want to know more about the man who made cinema history? Here are William Friedkin's 10 best quotes.
1. On the meaning of The Exorcist...
"With The Exorcist we said what we wanted to say. Neither one of us view it as a horror film. We view it as a film about the mysteries of faith. It's easier for people to call it a horror film. Or a great horror film. Or the greatest horror film ever made. Whenever I see that, I feel a great distance from it." | Getty Images
2. On authenticity in film....
"Style is something that's extremely important, but it must grow naturally out of who and what you are and what the material calls for. It cannot be superimposed." | Getty Images
3. On setting a mood...
"The first work of the director is to set a mood so that the actor's work can take place, so that the actor can create. And in order to do that, you have to communicate, communicate with the actors. And direction is about communication on all levels." | Getty Images
4. On stress...
"I don't know about the rest of you, but I feel pressed and tense almost every day of my life about something or other. And I think it's the one thing, as I look into people's eyes, that I think I share with almost everybody." | Getty Images