Longer books like “I have no mouth, but I must scream”?

I’m a big fantasy reader. I love Discworld, the Cosmere, The Wheel of Time, His Dark Materials, The Locked Tomb.

I recently came across I have no mouth, but I must scream and was immediately creeped out but intrigued by it. I’d love a suggestion of a longer book, either standalone or a series with the same kind of themes? Does anyone know of any?

by Kelsier0fHathsin