She's your number one fan. Annie Wilkes is horrifying because she is psychotic but she is a nurse - she can keep you alive for a looooong time in total agony. When she hobbled James Caan's character, Paul, the entire theater begged her to reconsider before screaming along with Paul. Not too many horror villains can make that happen.
Misery. A classic stalker film. Seen it loads of times. My friend lives with the nightmare of one of her obsessive fans dirty birding her one dark night when she drives home in her tank. She has spotters everywhere. They watch her via the Google Street Cam. They have maps charting hot spots. My friend is vulnerable to the nuts she works with, birds and cucumbers.