Doctor Cesspool is the main character in a comic series of the same name that was written by Nate Wright.
When Dr. Cesspool was a child, he loved baseball. He suffered from a near-fatal head injury when got hit by a line drive because they did not have batting helmets back then. His skull is now one-half steel. He is licensed as a qualified surgeon in 43 states.
Earlier in the comics from the 90s, Dr. Cesspool moonlighted as a crazed killer who wears a hockey mask and treats his patients poorly in the most sadistic way possible (i.e. amputating a patient because his head hurt). Thus he has the personality of a sadistic bully who finds twisted pleasure in harming others.
In modern comics and in the novels, however, Pierce removed the "murderer" element from Doctor Cesspool, and he became much nicer and less violent in modern comics and is depicted as more of an absent-minded and clumsy doctor who screws up trying to treat his patients. He also has a love interest, Maureen Biology.
Big Nate In A Class By Himself
Cesspool performed surgery on a woman (a nose job) and explained to her that she really didn't need a nose job. The woman is thrilled, and it is revealed that she does not have a nose.
Big Nate On A Roll
Dr Cesspool switched the positions of a man's hand and foot, and the man was furious.
Big Nate Goes For Broke
Cesspool performed surgery on the mayor and accidentally removed his stomach, calling it a "pesky little thing".
Behind the scenes