What do you call someone who collects cats?

Answer 1

In its mentally ill form it's called "Animal Hoarding". The typical person is a lonely, crazy old woman with a house full of cats, peeing wherever they wish.

Someone who lavishes lavishes affection on a reasonable number cats is often called a "Cat Granny". That's an insult, and can be applied to a male or female.

"Cat fancier" might be a neutral term. Their is a cat magazine called "Cat Fancy".

Answer 2

A person who collects cats is usually referred to as a "cat collector" or a "collector of cats."