You Won't Believe These 5 A-List Actors Once Walked the Halls of County General on 'ER'
Some of these actors appeared on the show long before they became famous.
ER is not only a legendary medical drama that attracted millions of viewers over 15 seasons, it was also a breeding ground for Hollywood talent.
While George Clooney, Julianna Margulies and Noah Wyle were the show's main stars, future superstars who were unrecognisable at the time could be seen flitting through the halls of the fictional County General Hospital.
1. Nick Offerman – Season 4 Episode 1
Nick Offerman's brief appearance in ER marked his television debut. The future comedian appeared in the fourth season, playing bassist Rog, who tries to help a fellow band member reach hospital.
This episode – the first and only one in the show's fifteen-year history – was filmed in a documentary style. The show's creators hoped this would give viewers a sense of what goes on behind the scenes in a real ER, where human lives are decided every day.
Offerman himself recalls the experience as rather pleasant and inspiring – he met George Clooney on set.
2. Lucy Liu – Season 2 Episode 5
Lucy Liu is another actress whose performance in ER is easily overlooked. She plays Mei-Sun, a quiet and vulnerable woman who unexpectedly arrives in the emergency room with her son.
She speaks poor English and knows even less about the American medical system. For a long time, the doctors are unable to diagnose the boy's illness, with Dr. Ross being particularly concerned about his health.
This story arc has a very sad ending: after extensive testing, the child is diagnosed with AIDS, and Mei-Sun is told that the disease is incurable.
3. Zac Efron – Season 10 Episode 3
Zac Efron's acting career began long before High School Musical, as evidenced by his appearance in ER. He was only 15 when he appeared in Season 10 and his performance is hardly memorable.
His character appears in the emergency room lobby, covered in wounds and bruises following a severe gunshot wound. However, Abby doesn't immediately realise how serious his condition is.
The episode ends tragically – the teenager dies in the trauma room.
4. Rooney Mara – Season 15 Episode 21
Rooney Mara makes a brief but emotional appearance in the 15th and final season of ER. Mara's character is minor and easily overlooked.
She plays a young mother named Megan who tells a disturbing yet relatable story for parents: her child is unwell but cannot yet express what is hurting them.
Even in this modest scene, Mara's acting style is evident: she experiences strong emotions internally while remaining almost unperturbed on the outside.
5. Ewan McGregor – Season 3 Episode 15
Ewan McGregor landed a guest role in ER long before he became famous for his role in Star Wars. He plays Duncan, a young criminal who decides to rob a convenience store with his cousin.
When the situation spirals out of control and a customer is seriously injured, only Nurse Carol can help. Ultimately, Duncan must make a difficult moral choice: help an innocent man and risk his own freedom, or escape responsibility.
Considered one of the most unusual episodes in the series, it sees much of the action taking place outside the hospital, with the entire drama revolving around two characters: Duncan and Carol.
