Created by novelist Michael Crichton and reportedly based on his own experiences as a medical student, the NBC hospital drama ER debuted September 19, 1994, directly opposite the similar CBS endeavor Chicago Hope. Though many critics thought that Chicago Hope had a better chance for survival than ER, the NBC series scored a surprise hit -- and over a decade later it was still firmly imbedded in the network's Thursday-night schedule, while Chicago Hope had long since vanished. Set largely in the emergency room of Chicago's fictional County General Hospital, ER focused on the professional and personal trials and tribulations of the unit's staff, with several subplots and story arcs weaving in and out of each hour-long episode. The regular cast for the first season consisted of Anthony Edwards as Dr. Mark Greene, George Clooney as Dr. Doug Ross, Sherry Stringfield as Dr. Susan Lewis, Eriq La Salle as Dr. Peter Benton, Julianna Margulies as Head Nurse Carol Hathaway, and Noah Wyle as med student (and later doctor) John Carter. Of these actors, only Sherry Stringfield and Noah Wyle would still be on the series as it entered its second decade on the air -- and of these two, only Wyle had been on the show throughout its entire run (Stringfield retired from the series in season three, but returned five years later).
Later principals, in order of their appearance, included Laura Innes as Dr. Kerry Weaver, Alex Kingston as Dr. Elizabeth Corday, Paul McCrane as Dr. Robert Romano, Kellie Martin as med student Lucy Knight, Erik Palladino as Dr. Dave Malucci, Goran Visnjic as Dr. Luka Kovac, Ming-Na as Dr. Jing-Mei "Deb" Chen (a recurring character in season one who returned as a regular in season six), Maura Tierney as Nurse (and later Dr.) Abby Lockhart, Michael Michele as Dr. Cleo Finch, Sharif Atkins as Dr. Michael Gallant, Mekhi Phifer as Dr. Gregory Pratt, and Parminder Nagra as med student (and later doctor) Neela Rasgotra. Many of these characters' lives were intertwined romantically, while some of the characters were bitter enemies; all were uniformly fascinating. And just as in "real life," there was nothing predictable about the exits of certain characters: some departed with tragic abruptness (Lucy Knight, Robert Romano), others simply bade farewell and moved on with their lives (Doug Ross, Carol Hathaway, Peter Benton); but no "goodbye" was as poignant and moving as the lingering illness and death of Mark Greene throughout the length and breadth of season eight. Though the plot emphasis was on the continuing characters, a number of prominent guest stars made memorable appearances during the series' decade-plus run. Alan Alda, Sally Field, and Bob Newhart were but three of the A-list entertainers who passed in and out of the doors of Chicago County. The winner of innumerable industry awards, ER has also earned a niche in media history as the most expensive dramatic series in TV history, reaching this particular plateau with its 13-million-dollar-per-episode average budget during the 1998-1999 season.