There isn't one universally accepted term for someone who loves cats, but here are a few options:
Formal
* Ailurophile: Derived from the Greek words "ailouros" (cat) and "philos" (lover). This is the most common and accurate term.
* Cat enthusiast: A more general and neutral term.
Informal
* Cat person: The most common informal way to describe someone who loves cats.
* Cat lover: Another common informal term.
* Crazy cat lady/man: Often used jokingly, but can be considered offensive or stereotypical.
* Cat fanatic: Implies a strong passion for cats.
The best term depends on the context and tone you want to convey.