Dr. James Wilson practices oncology in House M.D.
Wilson is the head of the oncology department at Princeton-Plainsboro Teaching Hospital and Gregory House’s closest friend. His specialty places him in a distinctive position on the show: he understands serious illness and mortality deeply, while also serving as a compassionate counterweight to House’s abrasive diagnostic style.
Oncology is the medical field focused on cancer, including its diagnosis, treatment, and management. Wilson’s work therefore brings him into contact with patients facing life-threatening disease, although the series often centers on House’s diagnostic department instead. The character is sometimes mistaken for a general physician or surgeon because he participates in many hospital cases. Robert Sean Leonard played Wilson, but the question concerns the fictional doctor’s specialty, not the actor’s profession or the hospital’s overall medical focus.