Which actor played James Wilson, Gregory House’s closest friend, in House M.D.?

Robert Sean Leonard played James Wilson in House M.D.

Wilson is an oncologist and the head of Oncology at Princeton-Plainsboro Teaching Hospital. He is House’s closest friend and often acts as a moral counterweight to House’s cynicism, impulsiveness, and disregard for social conventions. Their friendship is one of the show’s most persistent relationships.

Leonard appeared throughout the series and became central to several long-running storylines, including Wilson’s marriages, professional responsibilities, and eventual cancer diagnosis. His character’s medical specialty also creates a recurring contrast with House’s diagnostic work: Wilson treats cancer patients, while House investigates unexplained conditions.

Robert Sean Leonard was already known for film and theater before joining the series, including his role in Dead Poets Society. He is sometimes confused with Omar Epps, who played Eric Foreman, another important House colleague.