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 (TV series) on March 12, 2009, but NBC announced in January 2009 that it would extend the show by an additional three episodes to a full 22-episode order as part of a deal to launch a new series by John Wells titled "Police", later retitled "Southland". "ER"s final episode aired on April 2, 2009; the two-hour episode was preceded by a one-hour retrospective special. The series finale charged $425,000 per 30-second ad spot, more than three times the season's rate of $135,000. From season 4 to season 6 ER cost a record-breaking 13 million dollars. TNT also paid a record price of