Buttermilk is one of many identical locals seen in 12 oz. Mouse. He is a minor character that appears briefly in "Adventure Mouse", along with a friend, were admiring his new car until Roostre and company arrive at the scene piloting Fitz's "Jet Taxi", while violently crashing into them both. Buttermilk's new car was destroyed and both he and his friend were flash fried by the jet's flaming engines. He later reappears in "Francis, Cheap & Out of Control", as one of the several citizens attending Shark's party.
Buttermilk has the same basic character design of all the Human Citizens, he has a green shirt, blue pants, brown hair, same face, no nose or ears, colored white, His shoes are gray, he is wearing a black bow-tie and holding a bottle of beer/alcohol.