Formal:
* Bibliophile: This term literally means "lover of books" and encompasses all types of books, not just novels.
* Avid reader: This is a general term for someone who enjoys reading.
* Bookworm: Another general term, often used to describe someone who reads a lot.
Informal:
* Novel enthusiast: This is a more specific term for someone who enjoys reading novels.
* Fiction fan: This term is more general, as it encompasses all types of fiction, not just novels.
* Story lover: This term emphasizes the enjoyment of narrative.
You could also simply say "someone who enjoys reading novels."
The best term to use will depend on the context and your desired level of formality.