For me, The Exorcist. I watched in on parent's 50 inch tv when I was 17. I bought the movie from a mall an hour away when we went on a shopping trip. Lights off, no one home and it was terrifying.
Other offbeat favourites: Ginger Snaps, Blood the Last Vampire (animated), The Others, The Descent, Carrie 2013, original Child's Play, Friday the 13th 1-4, Freaky, The Lost Boys, Midnight Meat Train, Pumpkinhead, Sorority Row, Trick r Treat, VHS 2, You're Next, The Crazies 2010, Final Destination, Nightmare on Elm Street 1, 3 and New Nightmare, Funny Games 1997, Silver Bullet, thirst (bakjwi), and Vampire Hunter D bloodlust.
Slasher, Ash vs Evil Dead are decent tv shows. and The Terror season 1 for horror shows