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September 19, 1994
Season 1 begins, and will go on to win eight Emmys, including Juliana Margulies' for best supporting actress.
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September 26, 1996
Jeanie Boulet (Gloria Reuben) learns she has HIV; many other regulars will face their own health crises.
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May 14, 1998
ER gets its biggest audience ever — 47.8 million viewers — when it follows the Seinfeld finale.
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February 18, 1999
George Clooney leaves the show, but will return for a surprise cameo in 2000 for Margulies' ER swan song.
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September 30, 1999
Goran Visnjic joins the cast, eventually becoming the show's new romantic center with Maura Tierney.
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November 16, 2000
Sally Field plays Tierney's mom, and wins an Emmy. Future Emmy bait: Ray Liotta and Don Cheadle.
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May 9, 2002
Succumbing to a brain tumor, Dr. Greene (Anthony Edwards) is one of six hospital staffers to die thus far.
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September 25, 2003
Season 10 begins: Parminder Nagra, Scott Grimes, and Linda Cardellini will join the crowded ER.
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May 19, 2005
Last original cast member Noah Wyle leaves. Counting return cameos, he appeared in the most episodes: 254.
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November 10, 2005
John Stamos joins the show, picking up the "hunky doctor" mantle once carried by Clooney and Visnjic.
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April 2, 2009
After past castmembers returned to pay respects, the series ended on episode 332.
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By Abby West