Here's a scary thought: The following movies give William Friedkin, director of The Exorcist (pictured), nightmares. ''They're usually pursuit dreams. Somebody is after me to kill me,'' explains the Oscar winner and man behind 2007's Bug — now available on an EW Must List-approved special edition DVD — and the Dec. 6 episode of CSI (which he directed for friend William Petersen). ''I dread having these nightmares because they are so real to me that it takes me maybe hours after I wake up to convince myself that I'm not in that world,'' Friedkin says. ''These films produce that same effect every time I watch them.'' With that sobering endorsement, on to Friedkin's annotated list. Rent at your own risk.