For Navi, the left cat, we call her Chunka Munk, Plasticat, and Ms. Infected Lips.
For Scorpi, the cat on the right, we call him Mr. Small, Spider Cat, and Crybaby.
Our boys passed on several years ago but their nicknames were Munch and Wee. Short for munchkin and wee boy. Sometimes wed called them The Munch and The Wee, like they were important titles.