Jesse Spencer played Robert Chase, a member of House's original diagnostic team.
Chase is an Australian intensive-care specialist and intensivist who joins House's original team at Princeton-Plainsboro. He is part of the trio that also includes Eric Foreman and Allison Cameron, making him one of the show's earliest recurring physicians.
Chase's professional identity changes as the series develops. He becomes increasingly independent, takes on greater responsibility, and eventually becomes an important leader within Diagnostic Medicine.
A common mix-up is identifying Chase as one of House's later fellows. Characters such as Chris Taub, Lawrence Kutner, and Remy Hadley joined after the original team, while Chase belongs to the first group introduced in the series.