Jesse Spencer played Dr. Robert Chase from the first episode through the House M.D. series finale.
Robert Chase is one of House's original diagnostic fellows, introduced with Eric Foreman and Allison Cameron in the pilot. His medical background includes intensive care and surgery, and he becomes an increasingly experienced physician as the series progresses. Chase's professional path changes repeatedly, but he remains connected to Princeton-Plainsboro for most of the story.
Australian actor Jesse Spencer played Chase for all eight seasons. That makes Chase one of the longest-running members of House's diagnostic circle, even though the composition of the team changes several times. Spencer's performance also helped establish the character's shifting relationship with House's authority.
Chase eventually succeeds House as head of diagnostic medicine at Princeton-Plainsboro. This ending reflects his growth from a junior fellow into a senior doctor capable of leading the department. The other original fellows also have major arcs, but Foreman and Cameron follow different leadership and employment paths.