Dr. House's best-known hospital colleague and friend in House M.D. is James Wilson.
James Evan Wilson is the head of the Department of Oncology at Princeton-Plainsboro Teaching Hospital. He is portrayed by Robert Sean Leonard and functions as House's closest friend and a frequent moral counterweight. Wilson understands House's intelligence and humor but often challenges his cruelty, recklessness, and refusal to accept ordinary social limits.
Wilson's professional specialty also gives the series a distinct perspective on serious illness and end-of-life decisions. His relationships and marriages receive substantial storylines, while his friendship with House becomes especially important in the final seasons.
The character is often confused with House's diagnostic fellows, including Robert Chase and Eric Foreman. Those doctors work directly on House's diagnostic team at different points, whereas Wilson is an oncologist and department head. The two characters' friendship is a core continuing relationship throughout the series.