Noah Wyle remained a main cast member on ER for 11 seasons, outlasting his original co-stars who departed earlier to pursue other opportunities.
Wyle's character John Carter evolved from a medical student into an experienced doctor by the end of season 8. He chose to continue for three additional seasons.
In 2002 interviews, Wyle explained his decision. "I still feel like there's a lot to say and do with this character," he told Deseret News. He added in a UPI interview that the show allowed him to take film roles, which helped maintain his interest.
Other cast members left sooner. George Clooney departed after season 5, Julianna Margulies after season 6, and Sherry Stringfield after season 3, citing the demanding schedule.
Wyle later joined The Pitt, where recent cast changes include the departures of Dr. Collins after season 1 and Dr. Samira Mohan before season 3. He has stated plans to continue in the lead role.