Your child has caught the scary-book bug and keeps asking for one more spooky story. This is a real ladder: start at the bottom, where the monster is a living school and the fright is gone by bedtime, and climb only as far as your child wants to go. Each book asks for a little more nerve than the one before, and every single one is honestly graded, so you always know exactly how scary it is before you hand it over.
This is a scariness ladder, not a difficulty one, though reading level climbs alongside the fear. It opens with Eerie Elementary, where the monster is a building and the scare is pure fun, then steps into the first real chill with the original Goosebumps and the famous Scary Stories collection. From there it moves into atmospheric middle-grade horror — Small Spaces and City of Ghosts — where the dread lingers and there's grief and death under the frights. The last two rungs are the real thing: Coraline, one of the scariest children's books ever written, and The Graveyard Book, which opens on a murder and is the heaviest and most beautiful book here. Start wherever your child's nerve sits, and let them climb only as far as they want.