James Wilson is the oncology specialist and House’s closest friend in House, M.D. Robert Sean Leonard played Wilson throughout the series.
Wilson serves as the head of oncology at Princeton-Plainsboro Teaching Hospital. His medical specialty places him in regular contact with patients facing cancer, while his friendship with House gives him a different role in the story: he often challenges House’s decisions, offers emotional support, and absorbs the consequences of House’s behavior.
The friendship is one of the show’s most important long-running relationships. Wilson is generally more empathetic and socially conventional than House, but he is not simply a moral opposite; the series also depicts his own complicated relationships and mistakes. Their bond becomes especially important in the final season, when Wilson receives a terminal diagnosis.