The definition of scary changes from person to person. For some, it might be ghosts and haunted houses. For others, serial killers. For still others, the most frightening things are the ones that go bump in the night, unseen.

Despite the width of this spectrum, what unites all lovers of horror is the thrill that horror novels inspire within us: that universal sensation of your heart thumping out of your chest, as cold sweat breaks on your forehead when you turn the page.

To create this list, we went to the darkest, most ghostly corners of the literary world. Without further ado, here are the 100 best horror novels of all time — it’s safe to say that we hope they’ll keep you up at night. Happy reading!