I loved the Rats trilogy, I was absolutely terrified by it. Also, Carrie was good but as I got older I got more and more terrified of scarey movies, which has put a block on any modern horror novels. I love Frankenstein, Dracula and Handmaids Tale (not technically a horror novel, but it freaked me out!)...Margaret Atwood certainly puts her own spin on horror, which is chilling in a unique way.