In House M.D., Gregory House frequently plays the piano.
House is shown playing piano at home and using music as a private outlet. His musicianship reinforces the character’s intelligence and solitary habits, while also providing a contrast with his abrasive interactions at the hospital.
The series also depicts House playing guitar, so “piano” is the best answer when a question asks for the instrument he frequently plays without specifying a scene. Hugh Laurie himself is a musician and has performed piano and guitar in live and recorded settings.
The piano should not be confused with the diagnostic tools central to House’s work. Music is a recurring character detail, but the show does not present House as a professional concert musician. His performances are part of the domestic and personal side of the character.