In House M.D., who plays Dr. James Wilson, the oncologist and House’s closest friend?

Robert Sean Leonard plays Dr. James Wilson in House M.D.

Wilson is an oncologist and the chair of the hospital’s oncology department. He is also House’s closest friend, providing emotional support and an ethical counterweight to House’s confrontational personality. Their friendship is one of the show’s most consistent relationships.

Leonard was already known for major film and stage work before House M.D., including his role in Dead Poets Society. His performance as Wilson helped define the character as compassionate, socially capable, and willing to challenge House without abandoning him.

Wilson’s medical specialty is sometimes misidentified because he frequently participates in diagnostic discussions outside oncology. He is not House’s supervisor and is not the head of the diagnostic department. His recurring role is an oncologist who often becomes involved when a patient’s illness may be cancer-related.