Principal DeRosa is Caucasian, with large brown eyes, a tall face, wrinkled at the mouth, average height, and very broad. He is half bald and his little hair is dark brown. He wears blue pyjamas to bed, and is mostly seen wearing a dark brown jacket, a tan shirt, dark brown pants, and black shoes.
He is very grumpy, growling a lot, and shouting, saying things like "I'm gonna find you and eat your head for lunch!!" and other empty threats. He is also very strict, often putting students in detention, and he is very suspicious of Andy and Danny. He is also described by Danny as a "clean freak".