ER

By Emily Russin
Special to MSN TV

Since NBC announced that "ER" would end its run after its 15th season, speculation ran rampant as to which ex-cast members (ahem, George Clooney?) would grace Chicago's County General before the show flat-lined. And while some familiar faces have... more shown up as the equivalent of hospice to assist the Thursday night drama in its last breaths, there are many more unforgettable characters whose shadows never fully faded from the ambulance bay. The roster of actors who scrubbed in and convinced us they were fighting to save lives from the trauma trenches became faces we'd like to see in our own emergency situations. Here's a look back at cast members who were discharged along the way, but who made lasting impressions. The "ER" series finale airs April 2, in a special two-hour episode.

Related gallery: 'ER': Thanks for the Memories

(Sara De Boer/Retna Ltd;Camera Press/Retna Ltd;Leon/Retna Digital)