&quot;ER&quot; debuted on NBC on Sept. 19, 1994, ushering in one of the most popular medical dramas in TV history. Here's a look at what the cast is up to now, in honor of the 20th anniversary of &quot;ER's&quot; premiere.Pictured from Season 1 (l-r): Noah Wyle as Dr. John Carter; Sherry Stringfield as Dr. Susan Lewis; Anthony Edwards as Dr. Mark Greene; George Clooney as Dr. Doug Ross; and Eriq La Salle as Dr. Peter Benton.  Photo: NBC, Getty Images / Â© NBC Universal, Inc.