Doctor Moon is a criminal neurosurgeon who rents out his unethical skills to a variety of criminals. He is an expert in body modicifation, behavioral and torture. His employers have included the League of Assassins, Doctor Cyber and Tobias Whale, and though the first hero he faced was Batman, he is not strictly a Batman villain.
Doctor Moon was created by Dennis O'Neil and Irv Novick, first appearing in Batman #240 (1972).