House's oncologist best friend in House M.D. is named James Wilson.
Dr. James Wilson is played by Robert Sean Leonard and serves as the head of Oncology at Princeton-Plainsboro Teaching Hospital. His friendship with House is one of the show's most important long-running relationships. Wilson is generally more empathetic and socially accommodating than House, although he can also make ethically questionable choices.
The character's surname is Wilson, but the question asks for his first name. His full name is James Evan Wilson. The series frequently refers to him simply as Wilson, which is why viewers may remember the surname more readily.
Wilson's specialty is oncology, the branch of medicine concerned with cancer. He is not the hospital's neurologist or emergency physician, and he is not played by Hugh Laurie; Robert Sean Leonard portrays him across the series.