The original hit medical drama, ER, sure has had its fair share of actors walk through the doors of County General Hospital. Over the course of 15 seasons, the amount of patients, doctors, nurses, medical students, and secondary characters to appear on the show are endless. Whether you know it or not, ER served as a stepping stone for some actors and actresses that went on to become some of the biggest stars in Hollywood.
While you might think George Clooney was the only A-List star to appear, you might want to check your facts. Here are some actors you might not remember appeared on ER at some point between 1994-2009.
Ewan McGregor
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Kicking things off with a bang, the future young Obi-Wan Kenobi appeared on ER in a tense season 3 episode as one of two armed gunmen in a convenience store robbery gone bad. His appearance came not long after his breakout role in Trainspotting and just a few years before rising to fame in Star Wars Episode I: The Phantom Menace.
Alan Alda
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Serving as more of a M.A.S.H. easter egg, Alda briefly appeared in season 5 of ER as Dr. Gabriel Lawrence, a senior attending physician showing the beginning stages of Alzheimer’s.
Chadwick Boseman
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The future Black Panther himself appeared on ER in season 15 alongside Carl Weathers as a young amateur boxer with serious injuries.
Bradley Whitford
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Whitford had a brief arc on ER in seasons 1 and 2 as Sean O’Brien – a man who brings his pregnant wife into the emergency room and sues Dr. Greene for malpractice. The episode “Love’s Labor Lost” went on to win an Emmy Award for writing.
Aaron Paul
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Before hitting it big with Breaking Bad, Paul appeared in season 9 of ER as a teenage boy who was looking after his ill mother and siblings.
Tom Everett Scott
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Scott appeared in a recurring role as nurse Abby Lockhart’s brother, Eric Wyczenski, during season 9.
Forest Whitaker
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Whitaker appears in a multi-episode arc in season 13 as Curtis Ames – a County General patient who presented to the emergency room with a nagging cough. Ames went on to file a malpractice suit against the hospital staff for gross neglect.
Rooney Mara
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Before breaking out in the American version of The Girl with the Dragon Tattoo, Mara appeared on ER in 2009 as a young mother deciding whether or not she wants to give up her baby.
Lori Petty
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Petty made a brief appearance in season 8 as a pregnant drug addict who was fighting to retain custody of her baby.
Josh Hutcherson
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Way before capturing audiences as Peeta Mellark in The Hunger Games, Hutcherson briefly appeared in season 9 as a child fatally injured in an accident.
Rosemary Clooney
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That’s right, the famous aunt of ER star George Clooney appeared in a recurring role in the early days of the show. Clooney played Mary Cavanaugh, or Madame X, a singing elderly woman suffering from Alzheimer’s.
Don Cheadle
Cheadle’s guest appearance as medical student suffering from Parkinson’s Disease was captivating and heartbreaking all at once. Appearing in just a four-episode arc in season 9, Cheadle’s performance on ER earned him an Emmy nomination.
Eric Stonestreet
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Way before Modern Family, Stonestreet appeared in season 7 as a crazed Star Trek fan who… well, wanted to make himself look like Spock.
Zac Efron
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Just before Disney’s High School Musical, Efron appeared as a young boy who appeared at County General after suffering a gunshot wound.
Kal Penn
Appearing in season 7, Penn played a doctor at another Chicago hospital named Narajan. Luckily, this was before his breakout roles in House and the Harold & Kumar franchise. It was also before he became a White House staffer for former president Barack Obama.
Keegan Michael Key
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Key appeared very briefly as a member of Dr. Benton’s legal team in season 8.
Lucy Liu
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Before hitting it big with Charlie’s Angels and Kill Bill, Liu appeared in a multi-episode arc as Mei-Sun Leow, a woman who had a young child suffering from HIV/AIDS.
Emile Hirsch
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Before hitting it big with roles in Milk, Into the Wild, Alpha Dog, and The Girl Next Door, Hirsch appeared in two episodes during season 6 as Chad Kottmeier, a teenager struggling with alcohol abuse.
Chris Pine
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Way before being cast as Captain Kirk in Star Trek, Pine appeared in season 9 of ER as a drunk man in the emergency room.
Jared Padalecki
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Before rising to stardom in Supernatural, Padalecki appeared in season 7 alongside Jim Belushi as a young athlete who presented to the emergency room after the two got into a car accident.
C.C.H. Pounder
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Pounder has appeared on several TV shows such as Law & Order: SVU, and The West Wing, but she’s still fairly well known as surgeon Dr. Angela Hicks on ER. She starred in the recurring role up until season 4, leaving the show to pursue a film career.
Alex D. Linz
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After starring in hits such as Tarzan, Home Alone 3, and One Fine Day, Linz appeared in a season 7 episode as an adorably sweet young paraplegic boy .
Busy Philipps
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After gaining fame from shows like Dawson’s Creek and Freaks and Geeks, Philipps joined ER for a brief time as Dr. Hope Bobeck from 2006-2007.
Linda Cardellini
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Another Freaks and Geeks alum, Cardellini appeared from season 10 until the show’s finale as nurse Samantha Taggart.
Octavia Spencer
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Long before her Oscar-winning performance in The Help, Spencer appeared in a season 5 episode as a patient named Maria Jones.
Eva Mendes
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Long before her roles in Training Day, Ghost Rider, and Hitch, Mendes appeared in season 3 as a young babysitter who brings a little girl into County General Hospital.
Taraji P. Henson
Henson had not one, but two ER credits under her belt before hitting it big in projects like Hustle & Flow, Empire, and Person of Interest. She first appeared as Dr. Benton’s niece, Patrice Robbins, in season 4 and then again in season 5 as a young gang member.
Christina Hendricks
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Long before starring in Mad Men and Good Girls, Hendricks had a small recurring role in season 8 as nurse Abby Lockhart’s neighbor – a young woman being abused by her husband.
Kirsten Dunst
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Dunst had already skyrocketed to fame as a child star by the time she appeared on ER. After appearing in Little Women, Jumanji, and Interview with the Vampire, she appeared in a multi-episode arc in season 5 as a struggling homeless teenager named Charlie who befriends Dr. Ross. Shortly after ER, she went on to star in Drop Dead Gorgeous, Bring It On, and Spider-Man.
Gabrielle Union
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In season 6, Union appears as a high school basketball star who presents in the emergency room after a car accident.
Jurnee Smollett
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Smollett made a very brief appearance in season 9 as Romy, a teenager who attempts to abandon her baby in the emergency room.
Mae Whitman
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Whitman appeared in season 14 alongside her future Parenthood co-star, Miles Heizer, as a girl involved in an attention-seeking patient. Fun fact, Whitman starred alongside other ER alums Alex D. Linz and George Clooney in One Fine Day.
Swoosie Kurtz
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Kurtz appeared in season 4 as Tine Marine Chambliss, a televangelist’s wife using her chronic illness for personal gain.
Red Buttons
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Buttons’ appearance on ER definitely pulled on viewer’s hearts. Serving as the first harsh lesson for Dr. Carter, Buttons played Ruby Rubadoux – an elderly man trusting Dr. Carter to save his wife’s life, only to later blame him for her death. He appeared as the character throughout 5 episodes ranging from 1995-2005.
Thandie Newton
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ER was Newton’s first appearance on US television. The future star of Westworld appeared for a brief time as Makemba Likasu, a love interest of Dr. Carter and administrator of the Democratic Republic of Congo’s health ministry.
Shia LaBeouf
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Before his breakout role in Disney Channel’s comedy show Even Stevens, LaBeouf appeared in season 6 of ER as a young boy suffering from muscular dystrophy.
Anton Yelchin
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A young Yelchin appeared in season 6 as a young boy named Robbie Edelstein who loses his parents in a car accident. The brief role showcased Yelchin’s talent for intense, emotional roles, despite him only being 10-years old at the time.
Stanley Tucci
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Appearing as Dr. Kevin Moretti, Tucci had a brief multi-episode arc in 2007 when he came in as the short-lived Chief of Emergency Medicine.
James Cromwell
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Cromwell appeared in a recurring role throughout season 7 as Lionel Stewart – a local Catholic Bishop who appears in the emergency room on and off due to chronic illness. His storyline served as a secondary arc to Dr. Kovač’s crisis of faith. Cromwell went on to earn an Emmy nominator for the role.
Sally Field
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Perhaps one of the biggest celebrity guest stars on ER, Field had a recurring role as nurse Abby Lockhart’s mother, Maggie Wyczenski, from 2000-2006. Her appearance was complicated but praised for showing the struggle some endure with mental illness. In fact, she won an Emmy Award for the role in 2001.
Susan Sarandon
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In the show’s final season, Hollywood legend Sarandon appears as a grandmother who must decide whether she wants to pull life support for her grandson and donate his organs.