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.
My void was nicknamed Itty Bitty when I fostered him. Of course, he turned into a permanent family member and never got a new name. His full name became Itty Bitty Kitty.