What do you call someone who loves to read crime novels?

There isn't a single, commonly used term for someone who loves to read crime novels. However, here are some options:

Formal:

* Crime fiction enthusiast

* Mystery novel aficionado

* Devotee of detective fiction

Informal:

* Crime reader

* Mystery buff

* Hard-boiled fan

* Noir aficionado

Humorous:

* Sherlockian

* Poirot-phile (for Agatha Christie fans)

* Clue-hound

You can also be more specific based on the type of crime fiction they enjoy:

* Thriller lover

* Police procedural enthusiast

* Historical crime fiction fan

Ultimately, the best term depends on the context and the tone you're aiming for.