Cast of ER Cast of ER "ER" is an American drama series that aired on NBC from September 19, 1994 until April 2, 2009. The series featured a large ensemble cast that changed dramatically over its long run. The main cast was augmented by a wealth of recurring characters and award-winning guest stars. The original starring cast consisted of Anthony Edwards as Dr. Mark Greene, George Clooney as Dr. Douglas "Doug" Ross, Sherry Stringfield as Dr. Susan Lewis, Noah Wyle as medical student (later Dr.) John Carter, and Eriq La Salle as Dr. Peter Benton. Julianna Margulies guest starred in the pilot as
ER (season 15) ER (season 15) The fifteenth and final season of the American fictional drama television series "ER" premiered on September 25, 2008 and concluded on April 2, 2009, in a two-hour episode preceded by a one-hour retrospective special. The season consists of 22 episodes. The final season opens up revealing Gregory Pratt is the victim of the ambulance explosion. Despite the rallying efforts of his workplace colleagues, he succumbs to his injuries and dies. The season introduces Cate Banfield as new ER chief, a woman with a seemingly mysterious past with County General. Luka Kovac and Abby Lockhart leave for a