Gir

The only differences between Gir and regular ICU units are the unique coloration of Gir's luminous body parts (blue instead of red), and a different configuration for the eyes and striped mouth. His costume is a green dog suit with a zipper on the stomach and a head that can be removed like a hood. He also includes a small tail that in some unknown way he can wag like a real dog. His eyes are like those of a common human, black in color, he can open and close them sometimes, while other times he can't.

He is somewhat stupid and clumsy, he can be tantrum, he likes pizza and waffles, he is very innocent although sometimes not, he is fun and very very silly

Zim is Gir's master, green skin and a wig to try to camouflage himself among humans (a terrible disguise but no one seems to notice it)
He usually doesn't treat Gir well or barely tolerates him or yells at him.

Zim's nemesis, rebellious black hair, round black glasses, black trench coat, black boots, black pants, blue shirt and dark brown eyes, obsessed with the paranormal and tries to expose who Zim really is although no one believes him and they call him crazy, He is very intelligent and usually bored in class