Intro/Lore
People make many dog suggestions due to the fact of variety and practicality, where as cats, don't really do anything but leach off our resources... However in Tolkien's universe cats were more prevalent, look at Tevildo. Of course this was back in the elder days and cats aren't as big, but they are still evil creatures. I am here to suggest that cats are added as a separate mob than the current ones.
Interactions
Player: If you click a cat, it will hiss at you, maybe scratch (attack) you once and run away quickly.
Elves: If an elf sees a cat they will attack and try to kill it. (They really hate cats).
Men: They will ignore them.
Ents: An ent has a 1/5 chance to attack the cat.
Dwarves: They will ignore them.
Orcs: They will ignore but have 1/3 chance of attacking cats because they are violent creatures.
And of course cats will attack birds and dogs, maybe butterflies too.
Types
Dark cat: A breed of cat that lives in mordor, mainly around cities and fortresses where they live of scraps. Do 1 heart more damage and have red eyes.
Southron cat: They look like Egyptian Mau cats and are talked about by the Haradrim.
Western cat: They live around the Shire and Bree, they have a more molten pelt and found in taverns and such.