34 Actors You Forgot Were On 'Grey's Anatomy'

Episode: Season 2, episode 11: "Owner of a Lonely Heart"

Arquette made an early-series appearance in the second season, playing Constance Ferguson, a prisoner who swallowed razor blades in order to be admitted to Seattle Grace. She later swallows pieces from a broken lightbulb in order to prolong her stay at the hospital.

Episodes: Season 2, episode 16: "It's the End of the World"; season 3, episode 17: "Some Kind of Miracle"

Before he was Coach Taylor, Chandler appeared in two episodes of Grey's as Dylan Young. During the bomb scare, Young, a leading member of the Seattle Police Department Bomb Squad, was killed when an explosive went off in his arms after being successfully released from a body. Young later reappears in Meredith Grey's "afterlife" visions during her near-death experience in the series' third season. Dylan Young is the only character creator Shonda Rhimes regrets killing off in the series' 14-season run.

Episode: Season 2, episode 26: "Deterioration of the Fight or Flight Response"

Before Black Panther and Thor: Ragnarok, Thompson made a brief appearance as Camille Travis, Richard Webber's niece, in the series' second season. After passing out during sex the night of her prom. Camille finds out that her ovarian cancer has returned.

Episode: season 3, episode 3: "Sometimes a Fantasy"

Imagine a world in which you can't feel pain. Seems great at first, but in the third season Breslin played Morgan, a young girl who's insensitivity to pain means she has no gauge on how bad her injuries could be. After letting a classmate hit her stomach with a baseball bat 25 times, Morgan is admitted to surgery at Seattle Grace with internal injuries.

Episode: season 3, episode 19: "My Favorite Mistake"

Now you know her from Mad Men and The Handmaid's Tale, but back in 2007, Moss guest starred in the series' third season as Nina Rogerson, the daughter of a patient in need of a risky surgery who wants to make sure her mother receives the best care.

Episode: Season 4, episodes 3, 4, and 5: "Let the Truth Sting," The Heart of the Matter," and "Haunt You Every Day"

The late Hermann, most famous for playing Richard Gilmore on Gilmore Girls, appeared as Norman Shales, "World's Oldest Intern," on the third season. After thirty years in pharmacy, Dr. Shales enters Seattle Grace as an intern, where he is frequently confused for an attending due to his age. He suffers a stroke during surgery, and eventually transfers from surgical residency into psych, because he thinks all the surgeons could use a good shrink.

Episode: Season 4, episodes 5: "Haunt You Every Day"

The future 13 Reasons Why star played a young boy born with the ability to hear, but no external ears. Dr. Mark Sloan works to gather a team together at Seattle Grace in order to construct a pair for him.

Episode: Season 4, episodes 9 and 10: "Crash Into Me: Part 1" and "Crash Into Me: Part 2"

In one of the series' bloodiest moments, Green portrays Nick Hanscom, a patient who has an exposed carotid artery after a tumor resection in his neck. The tumor is successfully removed, but the carotid artery eventually bursts after Hanscom laughs a little too hard, and he dies. Dark, right?

Episode: Season 4, episodes 12 and 13: "Where the Wild Things Are" and "Piece of My Heart"

After her husband provokes a bear on a camping trip, Jennifer (DuVall) is attacked by the very unhappy bear and loses part of her scalp in the dust-up. Her husband is later diagnosed with a brain tumor that's causing impulsive decisions—like provoking bears.

Episode: Season 4, episode 12: "Where the Wild Things Are"

Yes, that Cheech. Marin played Otis Sharon, a man found collapsed on the street with a swollen ankle, and Izzie (Katherine Heigl) believes it's caused by a medical mystery. Turns out, it was just an ankle hairline fracture and a small flu.

Episode: Season 4, episodes 16 and 17: "Freedom, Part 1" and "Freedom, Part 2"

Before Underground, Smolett-Bell went above ground to Seattle Grace, where she played a young girl with an inoperable tumor. Both she and her boyfriend (who is suffering from the same tumor) came to Seattle Grace to participate in Derek and Meredith's clinical trial. She's the first person to survive the trial, but, sadly, her boyfriend does not.

Episode: Season 5, episodes 1 and 2: "Dream a Little Dream of Me: Part 1" and "Dream a Little Dream of Me: Part 2"

The Broadway legend appeared in two episodes of the show's fifth season. On her way to a ball, Sarabeth Breyers (Peters) gets into a car wreck in her limo with her girlfriends and she takes over driving the vehicle after the driver is injured. After finding out their husbands have been sent to rival hospital Mercy West, Sarabeth and her friends insist on going to Seattle Grace. Clearly, these are very happy marriages.

Episode: Season 5, episode 5: "There's No 'I' in Team"

Before his Tony-winning turn in Hamilton, Odom appeared in a fifth-season episode of Grey's Anatomy. Odom plays P.J. Walling, a man who finds himself a part of a domino kidney transplant after his ailing father offers him $10,000 for his kidney.

Episode: Season 5, episode 23: "Here's to Future Days"

Yet another Friday Night Lights alum to make a starring turn on Grey's, Gilford appears as a soldier looking for answers regarding the phantom pain in his leg after surgery.

Episode: Season 5, episode 23: "Here's to Future Days"

Now she's telling us How to Get Away with Murder, but in the series' fifth season, Weil appeared as Allison, Izzie's partner in chemotherapy. She initially reacts well to chemotherapy, but deteriorates rapidly, eventually falling into a coma she never wakes from.

Episode: Season 6, episode 15: "The Time Warp"

Season 6 episode "The Time Warp" is a flashback episode, following Paulson as Ellis Grey (mother of Meredith). The story recalls a case wherein a patient in 1982 was diagnosed with GRID, the virus we would later come to know as AIDS.

Episode: Season 6, episode 22: "Shiny Happy People"

The singer-actress made an appearance during the early stages of her career, when she was still known for Sonny with a Chance. Lovato played a character named Hayley May who had been incorrectly diagnosed with paranoid schizophrenia after discovering a tiny hole in her inner ear that led her to hurt herself. She later was diagnosed with Superior Canal Dehiscence Syndrome, and made a full recovery post-surgery.

Episodes: Four episodes total, season 6, episode 23: "Sanctuary,"; season 6, episode 24: Death and All His Friends,"; season 7, episode 6: "These Arms Of Mine" and season 7, episode 7: "That's Me Trying"

Already an established singer-actress, Moore first appeared on the show's two-part sixth season finale as a woman with terrible timing. The day she arrives at the hospital for a routine colostomy bag reversal surgery turns out to be the day the hospital shuts down because of an active shooter in the building. In lieu of the surgery, she opts to travel and delay the necessary procedure for six months. her storyline has a sad finale, however—she ends up in a coma after her surgery and her husband eventually takes her off life support.

Episode: season 7, episode 10: "Adrift and at Peace"

After The Real World, but before The Gifted, Jamie Chung appeared on Grey's. Chung play a newlywed named Trina Paiz on honeymoon in Seattle. Trina and her new husband stopped on a mountain to take a picture...and fell 100 feet into a ravine. She's got a lacerated ear, but her husband, Jason, is far more critical. They both survive their surgeries, but it was touch-and-go for a minute there.

Episode: season 8, episode 12: "Hope for the Hopeless"

Best known for My Big Fat Greek Wedding, Vardalos took a quick stop at Seattle Grace for a season 8 episode. Vardalos portrays Karen, who is in dire need of a liver transplant from her sister, Marcy. Marcy won't let Karen just have the liver, however. Marcy and Karen constantly bicker over what a good favor Marcy's doing for Karen, and Karen decides she doesn't want Marcy's liver if that's what it's going to take. That backfires swiftly, and Marcy winds up giving part of her liver to Karen and saving her life.

Episode: season 9, episodes 8 and 9: "Love Turns You Upside Down" and "Run, Baby, Run"

The House of Cards actress appeared in season 9 as one of Dr. Derek Shepard's sisters. Dr. Lizzie Shepard comes to Seattle Grace to donate a nerve to her brother after his hand injury in a plane crash.

Episode: season 9, episode 12: "Walking on a Dream" to season 9, episode 16: "This Is Why We Fight"

UnReal star Zimmer had a short stint on Grey's Anatomy as Dr. Alana Cahill, a brash physician's advisor brought in to save Seattle Grace from bankruptcy after the plane crash in the series' eighth season finale. She's ultimately unsuccessful in her endeavor—leading Catherine Avery and the Harper Avery Foundation to step in and save the day.

Episode: season 9, episode 19: "Can't Fight This Feeling"

Chalke left the Scrubs behind for this appearance. She appears as Casey Hedges, a mother whose son is sick but no one will believe her or diagnose his disease. She fights for her son, requesting multiple doctors, until finally she's given a true diagnosis.

Episode: Season 10, episode 16: "We Gotta Get Out of This Place"

Arriving at Grey Sloan Memorial 17, alone, and pregnant, Sheryll Jeffries (Palmer) desperately needs a heart transplant and came to join Cristina's clinical trial. She's told she's too old for the trial, and winds up going into labor prematurely.

Episode: Season 11, episode 15: "I Feel the Earth Move"

Two years before Stranger Things propelled her to international stardom, Millie Bobby Brown popped up on Grey's Anatomy as a young girl in a precarious position. After her mother fell and hit her head during an earthquake, Ruby (Brown) calls Grey Sloan Memorial with the hope of gaining medical attention for her mother, and winds up treating her mother herself with assistance from the Grey Sloan team...on the phone.

Episode: Five episodes from season 12, episode 17: "I Wear the Face" to season 12, episode 23: "At Last"

Valderrama appears as Kyle Diaz, a guitarist diagnosed with Multiple Sclerosis. He comes in with tremors to be treated at Grey Sloan Memorial, and stays awake playing the guitar during the subsequent brain surgery. He later returns with what appears to be meningitis, but after a series of complications, passes away in the season's penultimate episode.

Episode: Season 12, episode 14, "Odd Man Out"

The Happy Endings and "Bitch Sesh" comedienne made an appearance on a season 12 episode of Grey's Anatomy. She played Courtney Hall, a woman pregnant with quadruplets. Because two of the quadruplets had complications, Courtney was placed on bed rest, where she happily discusses taxes with the staff members.