• "ER" turns 28 on September 19 after originally premiering in 1994.
• The iconic George Clooney was part of the legendary original cast of "ER."
• Most of the main cast from "ER's" first season are still acting, too.

Anthony Edwards delivered a powerful performance as Dr. Mark Greene in NBC's "ER."

Dr. Greene was the leader of the pack at the show's fictionalized County General Hospital in Chicago, Illinois. He was established as chief resident in the show's very first episode.

He often made heavy decisions on behalf of the hospital and instructed his colleagues (most of whom were also his friends).

Over the course of his time on "ER," Dr. Greene had some marriage troubles and family issues. He eventually died from a brain tumor during season eight in one of the most heartbreaking deaths in TV history. 

Edwards earned four Emmy nominations for his role as Dr. Greene. He won a Golden Globe in 1998.

Although Edwards left "ER" in 2002 to spend more time with family, he has continued to act.

After leaving "ER," Edwards, 60, has been seen in a few different projects, including "Zero Hour" and "Law & Order True Crime: The Menendez Murders."

He made one last appearance on "ER" in 2008, reprising his role for an episode during the final season. 

In 2010, he won his first Emmy as an executive producer for the television movie "Temple Grandin."

Edwards produced and directed the 2016 film "My Dead Boyfriend." He also had roles in the Netflix miniseries "Inventing Anna" and the Apple TV+ miniseries "WeCrashed" in 2022.

Recently, Edwards performed in the Tony-nominated Broadway musical "Girl from the North Country."

He was also credited in this year's biggest box office hit "Top Gun: Maverick," and can be seen in archival footage. Edwards played Goose in the '80s original, the late father of Miles Teller's character and Maverick's best friend.

In 2021, he married Mare Winningham. The two worked together on "ER" during season five.

George Clooney portrayed the dreamy pediatrician Dr. Doug Ross. He was the heartthrob who was instrumental to "ER's" success.

Although Clooney was already a relatively well-known actor prior to "ER" (he got his start as the hunky handyman George Burnett on "Facts of Life"), playing Dr. Ross made him an icon. 

Well that, and the legendary Caesar haircut that he had while he was on the show. 

Throughout the show, Dr. Ross was a dedicated pediatrician who was extremely committed to his work. 

Although he was a womanizer who had a series of messy love affairs, Dr. Ross never let that affect his job. His most famous relationship was with Carol Hathaway, an ER nurse played by Julianna Margulies.

He eventually left "ER" midway through season five.

Clooney earned two Emmy nominations for his role as Dr. Ross.

Clooney left "ER" in 1999 to become an even bigger star, trading his starring role on the show for Academy Awards.

Soon after Clooney, 61, left "ER," he starred in multiple films in the 2000s, including "O Brother, Where Art Thou," "Good Night, and Good Luck," and the "Ocean's" trilogy, in which he played Danny Ocean.

His role in "O Brother, Where Art Thou" won him a Golden Globe for best actor in 2001. He also has two Oscars and six more Oscar nods under his belt. 

Clooney returned to "ER" twice: once in season six, to reunite with Carol Hathaway, and once in the final season to establish he and Hathaway were still together.

Alongside acting, he also founded the tequila brand Casamigos with his friend Rande Gerber in 2013.

The pair decided to start the company after they were unable to find the "perfect" tequila while vacationing in Mexico. Casamigos ended up being such a success that in 2017, Gerber and Clooney sold their brand for $1 billion dollars. 

In 2021, Clooney directed the film "The Tender Bar," which starred Ben Affleck. Later this year, he will be starring opposite Julia Roberts in "Ticket to Paradise."

Sherry Stringfield started off on "ER" as the bright-eyed Dr. Susan Lewis, a second-year resident at the hospital.

While Dr. Lewis was a capable and eager doctor, her lack of assertiveness sometimes allowed her to be pushed over by other doctors. She was good friends with both Dr. Ross and Dr. Greene.

During the series, Dr. Lewis had family troubles, like gaining and losing custody of her niece. This caused her much grief in season two.

A romance almost developed between Dr. Lewis and Dr. Greene, however before it was fully explored, Dr. Lewis moved to Arizona to be closer to her niece in season three. She wouldn't return to the show for years.

Stringfield earned three Emmy nominations for her role as Dr. Lewis.

In 2005, Stringfield told Variety that she was leaving "ER" because she was "ready for new roles and new challenges."

Stringfield, 55, returned to the show years later, and once again played Dr. Lewis from season eight to season twelve. She returned once more in the series finale.

Post-"ER," Stringfield has starred in a few television movies and series, including "Under the Dome" in 2014 and "Criminal Minds: Beyond Borders'' in 2016. That show ended in 2017, and Stringfield hasn't had an on-screen credit since.

Noah Wyle began the series as a third year medical student John Carter. He eventually became a doctor at the hospital.

Initially, Dr. Carter wasn't the most promising doctor, however his determination and compassionate nature helped him prevail.

He was mentored by Dr. Greene, and often found himself at odds with Dr. Peter Benton (Eriq La Salle), the resident he was assigned to.

Throughout the series, Dr. Carter had some tough moments — like in season six, when Carter and medical student Lucy Knight (Kellie Martin) were stabbed on the job by a schizophrenic patient. Knight died from her injuries and Dr. Carter struggled with survivors' guilt for years after.

Dr. Carter was one of the longest-lasting original characters from the first season "ER"  lineup, but eventually left after season 12.

Wyle earned five Emmy nominations for his role in "ER."

Wyle didn't miss a beat when "ER" ended, and has appeared in many projects since then, including "Below the Beltway," "W.," "Shot," and "Queen of the Lot."

Alongside those films, Wyle, 51, has starred in other television series such as "The Red Line" in 2018 and "Leverage: Redemption," in 2021.

Not only has Wyle continued acting, but he's also produced and directed some of the shows and films he performed in. From 2014 to 2018, he starred in "The Librarians," which he also executive-produced, directed, and wrote for. He also directed episodes of his TNT series "Falling Skies."

He also returned to "ER" for the 15th and final season.

Eriq La Salle played the arrogant and goal-oriented Dr. Peter Benton. He sometimes clashed with other "ER" characters during his time at the hospital.

Dr. Benton's strong personality resulted in him having conflicts with Dr. Carter and ER chief Dr. Romano (Paul McCrane). Sometimes, even viewers love to hate Dr. Benton.

Dr. Benton eventually left the hospital during season eight to get another hospital job with better money and hours.

La Salle earned three Emmy nominations for his role. 

After leaving "ER," La Salle continued to act, and has also directed multiple episodes of TV.

Shows that La Salle, 60, acted in after "ER" include "24," "How to Make It in America," "A Gifted Man," and "Under the Dome." 

He also has some producing credits on his resume, directing episodes for series like "Law & Order: Organized Crime," "Chicago PD," "Once Upon a Time," and "Lucifer."

Earlier this year, La Salle starred in the Hallmark original film "A Second Chance at Love."

La Salle also returned to "ER" a few times after his exit, most importantly during the final season in 2009 to reunite with former pupil Dr. Carter.

Julianna Margulies portrayed Carol Hathaway, an ER nurse and ex-girlfriend of Dr. Doug Ross.

In the first season, Hathaway is mainly recovering from her suicide attempt and getting over her feelings for Dr. Ross, her ex-boyfriend.

During the first few seasons, Hathaway tries to rebuild her life. Eventually, she found her footing, but faced many setbacks like getting suspended and financial trouble. 

Hathaway and Dr. Ross eventually get back together, but when Clooney left the show in season five, their characters broke up. Margulies left "ER" in season six, making every fan swoon when she finally reunited with Dr. Ross for good in the finale.

Margulies won an Emmy for her role in "ER" in 1995, making her the only actor to ever win an Emmy for the medical drama. She was nominated five more times after that.

Margulies is now starring on the Apple TV+ series "The Morning Show."

Before that Margulies, 56, starred in the Emmy-winning television series "The Good Wife." She won two more Emmys from four nominations for her performance.

The series was such a success that it led to the spin-off series "The Good Fight," which began its sixth and final season in September 2022.

Now, she co-stars with Reese Witherspoon and Jennifer Aniston in "The Morning Show" as the love interest of Witherspoon's character.

Alongside acting, Margulies is also an author. In 2016, she co-wrote the children's book "Three Magic Balloons." In 2021, she published her memoir "Sunshine Girl: An Unexpected Life."

Margulies and Clooney also returned during "ER's" final season to reassure fans that their characters were still together.

Ming-Na Wen portrayed Dr. Jing-Mei "Deb" Chen. She began as a medical student and ended as chief resident at the hospital.

In the first season, Dr. Chen was a medical student and had a rivalry with then-medical student Dr. John Carter. 

While she was a recurring character during season one, Wen didn't reprise her role until season six as a third-year resident, eventually becoming chief resident in season eight.

Over the course of the series, Dr. Chen had many ups and downs, like when she had to care for her sick father.

Dr. Chen left in season 11 after quitting the hospital, and was never heard from again.

Ming Na-Wen was recently seen in the Disney+ series "The Book of Boba Fett" as a formidable assassin.

Na-Wen, 58, has consistently acted since her departure from "ER." Besides "The Book of Boba Fett" and "The Mandalorian," she also starred in the Marvel TV series "Agents of S.H.I.E.LD.," "Young Sheldon," and Hacks."

Her voice has also been used in iconic animated films like Disney's "Mulan," and animated series like "Robot Chicken," "Phineas and Ferb," and the Disney XD series "Guardians of the Galaxy."

Na-Wen will also be in the upcoming projects "Gremlins: Secrets of the Mogwai," "Glitter & Doom," and "Persephone."

Gloria Reuben portrayed Jeanie Boulet, a physician's assistant at the ER. She later became the head of the HIV clinic.

In the beginning of the series, Boulet was a physical therapist who Dr. Benton hired to care for his mother. Although she was married at the time, she and Dr. Benton had a brief affair. 

Boulet ended up contracting HIV from her husband, and throughout the series she had to cope with the stigma of that diagnosis.

She left the hospital in season six to spend more time with her adopted son and family.

Reuben earned two Emmy nominations for her role. 

Reuben recently appeared on "The First Lady." She also starred in the 2022 film "Firestarter."

After "ER," Reuben landed roles in other major series including "Blindspot," "Cloak & Dagger," "Mr. Robot" and "City on a Hill." She also starred alongside fellow "ER" co-star Eriq La Selle in the film "A Second Chance at Love" in 2022.

In "The First Lady," Reuben played Valerie Jarrett, an advisor to President Obama.

Boulet also reappeared one more time during season 14 of "ER."

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