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
Cast of ER West returned for three episodes during Season 15 when his character reunited with Neela Rasgotra. Mekhi Phifer departed in the Season 15 premiere when his character, Gregory Pratt, died in the ER as the result of blast injuries suffered in an ambulance explosion in the Season 14 finale. Goran Visnjic, who played the character of Luka Kovač, departed in the season finale of Season 13 when he left for Croatia to care for his ailing father. He returned for seven episodes in Season 14 to wrap up his medical storyline and then made a brief appearance in Season 15's "Book