#2: The Exorcist

The Exorcist could have been my #1, but it may have come down to when I first saw it.  I was probably 14 when I first saw this, in the light of day and thus, it was nowhere near as scary as it may have been for someone else.  Great movie, unquestionably, flawless in every way.  It's even more unsettling if you see the director's cut (the spider-walk scene had me ready to crawl out of my skin). 

 

This movie takes its time to get you.  You're locked in for 2 hours, no need to rush anything.  And that's part of what makes it work.  You KNOW something bad is coming and you are slowly filled with dread in anticipation of what eventually happens.  I wouldn't call the climax scary, but it definitely worked.