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Almost every character in invincible is either a puppy character or a kitty character. Mark? Puppy, William? Also puppy, amber? Kitty. Rex is a kitty too but he's one of those hyper orange ones. Conquest is one of those fancy extra fluffy kitties.
Rick is a exception. He's some kind of lizard (not insultingly) angstrom is also a lizard (insultingly)
Shapesmith is one of those silly green alien cats that thinks it's a puppy