The surname of House M.D.’s oncologist James Wilson is Wilson.
Dr. James Evan Wilson is the head of oncology at Princeton-Plainsboro Teaching Hospital and one of the series’ most important supporting characters. Robert Sean Leonard plays him. Wilson is compassionate and socially skilled, creating a strong contrast with House’s abrasive behavior and unconventional methods.
The character’s professional specialty is oncology, the branch of medicine concerned with cancer. His work brings him into contact with patients facing serious illness, while his friendship with House repeatedly draws him into House’s personal and professional crises.
The answer is simply Wilson because the question asks for the character’s surname, not the actor’s name or medical specialty. Foreman, Chase, and Taub are other doctors associated with House’s diagnostic teams, but none is James Wilson. His full name is James Evan Wilson.