Can you believe ER premiered 20 years ago today? It seems like just yesterday the show, which ran from 1994 to 2009, made its debut. The show introduced us to newcomers Julianna Margulies and George Clooney (above), who played Nurse Carol Hathaway and Dr. Doug Ross in the hit TV series that followed a group of emergency room doctors as they worked at a Chicago hospital. We couldn't help but dig up the above vintage snapshot of Clooney and Margulies on the ER set. Although we tuned in for the drama, most of us stayed for Hollywood's favorite bachelor (now husband-to-be!), who went through a number of hair changes through his career.