There's no denying that William Friedkin's 1973 film The Exorcist remains one of the most horrifying films ever made, and we just can't imagine how terrifying it was for those first audiences more than 40 years ago.
All of the elements come together to make it so - Friedkin's often harsh directing, the source material from William Peter Blatty, committed performances from Linda Blair and Max von Sydow (among others) and the relatively recent relaxation of the production code which let filmmakers go wild in the early 70s. Another important aspect is the music, which uses several classical pieces and, most memorably, Mike Oldfield's Tubular Bells. That song actually isn't in the film for long and only became a massive success after it's apperance in The Exorcist.
But the film might have had a more conventional score, with veteran composer Lalo Schifrin originally hired. He's worked on everything from Cool Hand Luke to Rush Hour, with hits like Dirty Harry Mission Impossible and more in between. Schifrin created some music for the Exorcist's original trailer and was hired to score the entire film but, according to legend, famously difficult director Friedkin threw out the recording and the relationship fell apart.
That score has recently resurfaced and you can hear a sample of it below. There's no doubting it's creepy and actually very intense, maybe the film would have been even more terrifying with tunes behind it? We'll never know. You can also see the banned trailer with this score below.