In House M.D., what is the name of Dr. Gregory House’s closest friend?

In House M.D., Dr. Gregory House’s closest friend is James Wilson.

Dr. James Wilson is an oncologist at Princeton-Plainsboro Teaching Hospital and is played by Robert Sean Leonard. Wilson is one of the few people willing to challenge House directly while continuing to understand his intelligence and vulnerabilities. Their friendship is central to the series, even when House's choices create serious personal or professional damage.

Wilson's medical specialty also creates an important contrast with House's diagnostic work. As an oncologist, Wilson treats patients with cancer, while House's team investigates unexplained illnesses across many specialties. Wilson's personal life is repeatedly affected by his loyalty to House, including conflicts involving relationships, hospital policy, and House's legal troubles. In the final season, Wilson is diagnosed with terminal thymoma, and his illness becomes the emotional foundation of the series finale.