'ER's' Emmy-nominated guest stars
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By Paul Sheehan
Over the first 14 seasons of "ER," 20 guest performers have earned 21 Emmy nominations. Surprisingly, only two have won -- Sally Field for the first of her two nods as the bipolar mother of cast regular Maura Tierney in 2001 and Ray Liotta for his stunning 2005 portrayal of the last hours in the life of an alcoholic.