George Clooney's Dr. Ross returns to `ER'

George Clooney has led a parade of old favorites back to "ER" as the medical drama nears the end of its 15-year run.

Clooney, whose character Dr. Doug Ross left the show in 1999, returned in Thursday's episode. The doctor, now in Seattle, works with wife Carol Hathaway (Julianna Margulies) to persuade a grandmother played by Susan Sarandon to donate the organs of her grandson.

Eriq La Salle and Noah Wyle, two other original cast members, also appeared in Thursday's episode.

The finale of the NBC drama is scheduled for April 2. Once television's most popular show, the series now draws about one-fourth the audience each week that it had during its peak.