Melvin is a large, barely tamed slave rat and loyal companion to Dr. Egg Man. He is an efficiently built living experiment, part of Dr. Man's Rat Enslavement Serum Program. Powered by steam and preserved by formaldehyde, Melvin is immortal.
He is often vicious upon sight and is willing to attack with savage brute force and dirty tactics. It is said he once choked a man with his tail while simultaneously scratching him with his 2 inch long talon-like claws. A sound similar to a cat screeching is his battle cry amidst his chaotic quarrels.