Frankenstein; or, The Modern Prometheus

This is the one where ambition runs ahead of conscience. A young scientist becomes obsessed with the idea of creating life from dead matter, works himself half to death getting there, and then, the moment it actually breathes, panics and bolts. It's less "monster on the loose" than "man makes something enormous and has absolutely no plan for what comes next", which honestly feels very true to life.

The horror here creeps rather than jumps. It's dread built from guilt, isolation and a slow unravelling, with the body horror sitting quietly under the surface rather than shoved in your face. No one leaps out of a wardrobe. You just feel the walls closing in on someone who has done something he can't undo.

Good for a properly dark, quiet night when you want to sit with something rather than yelp at it. Tea, a blanket, low light, no interruptions.

It's told through letters, which I love, layers within layers, someone telling someone else's story. And it's worth remembering this is where a lot of science fiction as we know it starts. Mary Shelley basically invented a genre while other people her age were still deciding what to have for breakfast.