50 Famous Actors You Probably Forgot Were on 'Grey's Anatomy'

So much drama, so many cameos.

Bet you didn't remember Millie Bobby Brown appeared in an episode.

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ABC
Mandy Moore

As patient Mary Portman, Moore was present for one of the most dramatic episodes in Grey's history (and that's saying a lot): the Seattle Grace Mercy West shooting. She returned the following season for a surgical procedure; her character died after slipping into a coma. (Seasons 6 and 7.)

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ABC
Faye Dunaway

She played the first female surgeon at Seattle Grace Hospital, Dr. Margaret Campbell. After botching a surgery—and then repairing it—she decided to retire. (Season 5.)

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ABC
Jennifer Westfeldt

After accidentally running over her husband and bringing him to the hospital, a pregnant Jen (also the character's name) collapsed and later had a seizure due to an aneurysm. She went into surgery, during which she was given a blood transfusion that put her pregnancy at serious risk. Ultimately, she died and the baby lived. (Season 5.)

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ABC
Constance Zimmer

The House of Cards and Entourage actress played Dr. Cahill, a physician brought in to make the hospital run more efficiently. (Season 9.)

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ABC
Christina Ricci

She played a paramedic who had to keep her hand on a wound lest she detonate a bomb that was inside the patient. Yes, really. (Season 2.)

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ABC
Jurnee Smollett-Bell

As Beth Monroe, she came to the hospital with an inoperable tumor and was the first patient to survive Derek and Meredith's clinical trial. Her boyfriend Jeremy was also part of the trial; he died. (Season 4.)

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ABC
Kyle Chandler

He was the head of the bomb squad and died trying to carry the bomb out of the hospital. (Season 2.)

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ABC
Abigail Breslin

The Little Miss Sunshine and Scream Queens star played a little girl who was immune to feeling any pain. (Season 3.)

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ABC
Elisabeth Moss

The Mad Men and Handmaid's Tale star played an overprotective and slightly unhinged daughter whose mother suffered from a condition that caused bone to grow at the site of an injury. The mom died in surgery. (Season 3.)

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ABC
Jesse Plemons

The Friday Night Lights alumnus played Jake Burton, a young man with craniodiaphyseal dysplasia. The bone disorder, "lionitus," causes calcium to build up in the skull, leading to facial disfiguration. In Jake's case, the growth moved inward as well, and Derek was tasked with removing the resulting brain tumor. Jake died in surgery. (Season 2.)

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ABC
Zach Gilford

FNL star Gilford played a lieutenant in the U.S. Army who came to the hospital with terrible leg pain, asking for an amputation. Even though she could find nothing wrong with the leg, Callie Torres agreed to perform the surgery so he could return to active duty. (Season 5.)

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ABC
Sarah Chalke

The Scrubs actress played the mother of a sick boy whom Jo Wilson wrongly diagnosed with strep throat. The kid in fact had a rare heart condition, Kawasaki disease, which Jo caught just in time to prevent permanent damage, mostly thanks to the boy's persistent mom. (Season 9.)

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ABC
Michaela Watkins

She played Nikki, a woman who fell out of a tree, where she was stationed to spy on her ex-boyfriend, then refused to have surgery due to superstition. She died. (Season 2.)

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ABC
Katie Lowes

She played a blood donor in the show's seventh season and went on to have a much bigger role in the Shondaverse as Quinn on Scandal.

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ABC
Alexandra Billings

The Transparent star plays Donna Gibson, a trans woman who was diagnosed with breast cancer. (Season 3.)

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ABC
Ken Marino

Marino played Brad, a man who literally dodged a bullet when a disgruntled ex-employee showed up at his restaurant with a gun. Brad was leaving the hospital when Petey appeared again—and this time killed him. (Season 2.)

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ABC
Maggie Siff

The Sons of Anarchy star played Ruthie, a woman with severe osteoporosis caused by malnutrition. (She'd lost 40 pounds to meet her boyfriend's criteria for moving in together.) She died after vomiting up blood due to a bleeding ulcer. (Season 4.)

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ABC
Danny Strong

The Buffy and Gilmore Girls star (and TV and movie writer) played Paul, a guy who thought he was meeting his girlfriend's cat—and it turned out that her cat was a lion. (Season 8.)

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ABC
Leslie Odom Jr.

Before becoming a Broadway god as Aaron Burr in Hamilton, Odom played a young man who begrudgingly agreed to donate a kidney to his father. (Season 5.)

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ABC
Rich Sommer

The Mad Men star played a driver's ed instructor who saved his girlfriend's son's life by getting him to the hospital in time. (Season 12.)

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ABC
Doris Roberts

The late, great Everybody Loves Raymond matriarch played a patient with lung cancer who donated $200,000 to Alex Karev's African orphans projects. (Season 7.)

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ABC
Bernadette Peters

As Sarabeth, Peters and her friends were on their way to the Fire and Ice Ball when their limo crashed. She found out her husband was cheating on her, but nobody died. (Season 5.)

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ABC
Seth Green

Green's two-episode arc ended with his character dying; he had a tumor on his carotid artery. (Season 4.)

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ABC
June Squibb

The veteran actress, who's recently blessed Girls and Shameless with her presence, played Elsie Clatch, a 95-year-old woman who undergoes surgery for a brain bleed and dies, leaving behind her husband of decades. (Season 13.)

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ABC
Heather Matarazzo

The Welcome to the Dollhouse and Princess Diaries actress played a woman who survives a tunnel collapse. What makes it that much more intense was that she was in labor and on her way to the hospital when the accident happened. (Season 11.)

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ABC
Laurie Metcalf

Metcalf played a woman with terminal cancer who had yet to tell her young daughter she was sick. (Season 2.)

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ABC
Scott Foley

The Felicity and Scandal star had a recurring role as Teddy Altman's husband, whom she met in the hospital when he was her patient. (Season 7 and 8.)

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ABC
Geena Davis

The A League of Their Own legend played Dr. Nicole Herman, a surgeon with only six months to live who chose to impart some of her rarest medical wisdom onto Arizona Robbins. (Season 11.)

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ABC
Dylan Minnette

Before 13 Reasons Why, Minnette played a precocious kid named Ryan, who was born with only internal ear parts and showed up to Seattle Grace to ask Mark Sloan to build him ears for free. (Season 4.)

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ABC
Frances Conroy

The Six Feet Under star played a woman who purposely ran her car into a laundromat after seeing her estranged husband's mistress through the window. She mistakenly admitted her crime to the doctors, thinking they couldn't tell the police due to confidentiality laws. (Season 7.)

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