Which actor portrays oncologist James Wilson in House M.D.?

Robert Sean Leonard portrays oncologist James Wilson in House M.D. Wilson is Gregory House’s closest friend and serves as a major emotional and ethical counterweight to House’s confrontational personality.

As head of oncology at Princeton-Plainsboro, Wilson treats patients with cancer and frequently consults on House’s diagnostic cases. His friendship with House survives arguments, deception, and repeated boundary violations, although the series often tests how much Wilson is willing to tolerate. Wilson is generally more empathetic and socially conventional than House, but he also has personal flaws and complicated relationships.

Leonard was already known for films and stage work before joining the series. He appeared in Dead Poets Society and later received a Tony Award for his performance in The Invention of Love. In House M.D., Wilson’s medical specialty is oncology, while Leonard’s role is that of an actor portraying a fictional physician—not a real practicing oncologist.