"Night of the Living Dead" (1968) and "Dracula" (the 1992 Gary Oldman/Keanu Reeves version). Tie, for me. I could probably get through the first one now (then again, maybe not!), but I know I can't watch the second. I can't even watch when others are watching. The coffin of dirt racing along the cliff scene... the lady vampires eating the baby - yowsa! Sends {{{{{{{{{{mega-shudders}}}}}}}}}} up and down mine spine just thinking of it!
"Alien" was also a bit much for me at the time. I had to watch Alien 2 and Alien 3 (both of which I LOVED) before I could get up the nerve to go back and re-watch the first one.
Oh! Oh! I know, I know! "Trilogy of Terror"! (1975). All four vignettes were creepy but one had this little voodoo doll that came to life when its totem necklace fell off. Ooh-wee, talk about a mean little ugly voodoo doll! Made "Chuckie" look no more harmful than Ken on a bad-hair day...
Scary movies are... scary.
Peace!
SA, on her own...