Top scary movies to my view:
5. Alien. Big rollercoaster ride of a movie. I actually liked Aliens better, but Aliens was an action flick, and Alien was more of the classic horror thing going on.
4. Jaws. I lived in California when this came out. In a beach culture, it actually changed how people related to their otherwise normal activities.
3. Invasion of the Body Snatchers, the one with Donald Sutherland. Wow, those expressions and that sound.
2. Halloween. The first of the modern slasher genre, and the best.
And here I must mention The Exorcist, which Grandma would put in her top five; our gracious host's Carrie and for someone else, maybe, The Shining; Arachnophobia, except I considered it as much of a comedy as horror flick.
And for my No. 1:
Psycho. This one changed how people watched movies. No audience before or since has been so involved, so taken in, with screams from their seats as the heroine gets killed halfway in, and even, "No! No!" as the car with her body stops sinking for a moment, and Hitchcock cons audiences into rooting for the villain. And it changed moviemaking as well. Psycho begat many other movies, including the above-mentioned slasher genre, even though no one else ever did it as well, and especially with the shocker at the end. This one stands out as a true movie masterpiece.