As one of the longest-running medical dramas in history, “Grey’s Anatomy” has had plenty of opportunities for guest stars. During its lengthy run, the show — now in season 15 — has featured a ton of notable names, from Demi Lovato to Kyle Chandler.
Here’s a look back at some the famous actors you probably forgot once appeared on “Grey’s Anatomy.”
Way back in season three, Elisabeth Moss played Nina Rogerson, an overprotective daughter of a Seattle Grey’s patient. Her mother suffered from a condition that caused bones to grow at the site of any trauma. Sadly, her mom died while undergoing a risky surgery at the hospital.
The singer and actress played psych patient Hayley May in a season six episode. Hayley was incorrectly diagnosed with paranoid schizophrenia, despite her insistence that her condition wasn’t mental health-related. Alex eventually helped her uncover her real diagnosis, and she underwent surgery that allowed her to function normally.
The “American Horror Story” star played a younger version of Meredith’s mother, Dr. Ellis Grey. She made her appearance during the season six flashback episode, “The Time Warp.” The episode revealed more details about Ellis’ relationship with Dr. Richard Webber.
In season two, the former “Friday Nights Lights” star appeared as Dylan Young, a leader of the Seattle Police Department Bomb Squad. Sadly, his character died while attempting to carry a bomb out of the hospital. He later reappeared in season three as a vision to Meredith, after she fell into Elliott Bay and entered an afterlife-like dimension.
Mandy Moore’s first appearance as patient Mary Portman took place during one of the show’s most dramatic moments: the shooting at Seattle Grace Mercy West captured in season six. She and Dr. Bailey were locked in a room together during the emergency and tried to save Charles Percy after he was shot. Portman returned in season seven to undergo a surgical procedure but passed away after slipping into a coma.
Millie Bobby Brown
Before she became a household name as a star on “Stranger Things,” Millie Bobby Brown guest starred on season 11 of “Grey’s Anatomy.” The actress played Ruby, a young girl whose mother fell and hit her head while visiting their cabin. Unable to reach 911, Ruby called the hospital and treated her mother by following Owen’s instructions over the phone.
In season four, Seth Green played Nick Hanscom, a patient who was left with an exposed carotid artery after the removal of a large tumor. While joking with Lexi, Nick’s unprotected artery ruptured. Though the doctors did their best to stop the bleeding and save him, he was eventually pronounced dead.
Abigal Breslin played young patient Megan Clover in season two. Megan’s foster parents initially brought her into the ER for an injury. After examining her, the doctors discovered a range of other injuries and realized she had CIPA, a condition that made her immune to pain.
These days, you probably know her from “Creed” or “Thor: Ragnarok,” but Tessa Thompson was also once a “Grey’s Anatomy” guest star. She played Camille Travis, the niece of Richard Webber, who was rushed to the hospital after losing consciousness while having sex on her prom night. It’s revealed she is an ovarian cancer survivor, having initially been diagnosed at age 14.
June Squibb portrayed Elsie Clatch, a patient who was brought into the hospital after a syncopal episode. In a season 13 episode, the character underwent surgery to alleviate a brain bleed. Though she appeared to be doing well after waking up from her surgery, she died suddenly later that same day.
The “Empire” creator played Paul on season eight of the series. He came into the E.R. after being mauled by his girlfriend’s pet lion. The doctors were able to successfully treat his injuries with surgery.
In season two, Christina Ricci’s paramedic character, Hannah Davies, had an incredibly strange and terrifying task — even by “Grey’s” standards. She had to keep her hand on a wound in order to avoid detonating a bomb inside a patient. Thankfully, Cristina and Meredith eventually jumped in to help her and the patient was saved.
Before returning to her “Roseanne” roots on “The Conners,” Sara Gilbert made an appearance in season six of “Grey’s.” The actress played Kim, a woman with terminal cancer. She decided to end her life through physician-assisted suicide, sparking a debate among the doctors about the morality of her decision.
Neve Campbell played one of Derek’s four sisters, Liz. In season nine, Liz arrived at Seattle Grace to donate some nerves for Derek’s surgery on his damaged hand. Callie and Jackson eventually realized that more nerves from Liz’s calves were also needed for Derek’s hand to regain function, but the operation still went through as planned.
Wilmer Valderrama guest starred on season 12 as Kyle Diaz, a musician who struggled with multiple sclerosis. He came into the hospital to undergo brain surgery that would stop his hand tremors. He also briefly dated Stephanie Edwards.
In season three, “Parenthood” star Mae Whitman portrayed Heather Douglas, a patient who suffered from severe scoliosis caused by VATER Syndrome. Though she agreed to undergo risky spinal surgery to correct the problem, her insurance company refused to pay for the procedure. The surgery was later rescheduled after an anonymous donor agreed to pay the entire bill for her hospitalization and rehab.
The “Scandal” star made a brief cameo in season seven. In the episode “Unaccompanied Minor,” she portrayed an unnamed blood donor.
Leslie Odom Jr.
Long before he starred in the Broadway hit “Hamilton,” Leslie Odom Jr. made an appearance on season five of “Grey’s Anatomy.” He participated in a domino kidney transplant at the hospital. He ended up donating his kidney to another participant, Stan Mercer.
Season two featured actress Laurie Metcalf as Beatrice Carver, a patient with terminal cancer. After undergoing surgery, she tried to leave the hospital in order to see her daughter, whose birthday was the following day. Alex eventually convinced her to stay.
In season five, Bernadette Peters played Sarabeth Breyers, a patient at Seattle Grace. She and several friends got into a car accident on the way to an event. Though she managed to escape with no serious injuries, the incident did result in her uncovering her husband’s affair with her best friend.
The “13 Reasons Why” actor was just a kid when he made an appearance as a Seattle Grace patient in season four. In the episode, he played Ryan, a child born with no external ears. With a little help from Meridith, Mark Sloan ended up reconstructing Ryan’s ears.
Faye Dunaway brought her star power to season five of “Grey’s Anatomy.” She played Dr. Margaret Campbell, the first female surgeon at Seattle Grace Hospital. After making a mistake during a patient’s surgery, she performed her last ever procedure to fix the problem.
Before co-starring on“NCIS: Los Angeles,” Chris O’Donnell played Finn Dandridge on “Grey’s Anatomy.” The veterinarian character briefly served as Meredith’s love interest in seasons two and three. He even attended the hospital prom with Meredith, but she ended up ditching him for Derek.
Ken Marino popped up in season two of “Grey’s” as a restaurant manager, Brad Ackles. In the ER, Izzie treated Brad’s injuries after he got shot by a disgruntled former employee. Though the wounds he sustained were not serious, he later died when the ex-employee fired a gun at him again as he left the hospital.
A few years after wrapping up her run on “Everybody Loves Raymond,” the late Doris Roberts made a season seven appearance on an episode of “Grey’s.” She played Gladys Pulcher, a wealthy woman with lung cancer. She came to the hospital after her surgery did not go as planned.
In season 10, Keke Palmer played Sheryll Jeffries, a young woman who ran away from home after getting diagnosed with hypoplastic left heart syndrome. She became pregnant after running away, leading her to finally seek treatment for her condition. Though she attempted to join Cristina’s trial on the disease, the doctor declined her request.
The “Gilmore Girls” and “How to Get Away With Murder” star made an appearance in season five. She portrayed Alison Clark, a cancer patient who befriended Izzie Stevens while they were undergoing chemotherapy together. She coded during emergency surgery and remained on a ventilator until doctors confirmed she likely wouldn’t ever wake up.
A season two episode featured Michaela Watkins as Nikki Ratlin, a woman who entered the hospital after falling out of a tree. Though her injuries required immediate surgery, the superstitious patient refused to allow doctors to operate until the following day. Despite the doctors’ attempts to change her mind, she wouldn’t budge and ended up dying later that night.
Scott Foley made an appearance on “Grey’s Anatomy” before going on to star in another Shonda Rhimes hit, “Scandal.” The actor had a recurring role as Henry Burton in season seven and eight of the drama. He played Teddy Altman’s husband, who she first met while he was a patient at the hospital.
The “Happy Endings” star played Courtney Hall, an accountant pregnant with quadruplets in season 12. When she went into labor early, Arizona was forced to deliver one of the babies. But she was able to stop the delivery of the other three to give them a chance to continue developing.
Even megastar Rita Moreno has made an appearance on “Grey’s” during the course of its lengthy run. The actress was a guest star on season 12. She portrayed Gayle McColl, the estranged wife of a man who entered the hospital after running his car into an electric pole.
Jamie Chung — who came into fame via MTV’s “The Real World” before her roles in films such as “The Hangover Part II” and “Big Hero 6” — joined “Grey’s Anatomy” for an episode in season seven. Her character, Trina Paiz, found herself in the hospital after falling 100 feet into a ravine while on her honeymoon. She got treated for a lacerated ear while her husband, who also endured the fall, underwent serious surgery.
The late star appeared in a season two episode as patient Sylvia Booker. She entered the hospital after an embarrassing incident left her with a fork in her neck. While there, she also revealed that she had a seemingly inoperable aneurysm, which Derek was able to successfully perform surgery on.
“That Thing You Do” and “Can’t Hardly Wait” star Ethan Embry guest starred in the show’s ninth season. He played David Moore, a prosthetist at Seattle Grace. David worked with Arizona following the above-the-knee amputation of her left leg.
The “My Big Fat Greek Wedding” star appeared in season eight. She played Karen, a patient suffering from liver failure. She underwent a kidney transplant after her sister was discovered to be a match.
Mary Pat Gleason
In season 10, Mary Pat Gleason played Marge Walker, a patient suffering from an infected bug bite. After putting off her visit to the hospital for months, the infection turned serious. As Meredith treated her, she tried to distract Marge, who was afraid of hospitals.
The “Gilmore Girls” and “Parenthood” actress portrayed a marriage counselor in season 11 of “Grey’s Anatomy.” Her character, Dr. Kim Dawson, helped Callie and Arizona work out some of their relationship issues.
Before becoming a series regular on “Scandal,” Josh Malina popped up in Shonda Rhimes’ original hit show. In season five, Malina played Seth Hammer, the distraught husband of a patient. He brought his wife to the hospital after she began suffering from severe abdominal pain.
In season eight, Lee Majors played Chuck Cain, a patient who came into the hospital in need of surgery. While preparing for the procedure, Lee became overly concerned about the possibility of having an ugly post-op scar. He proposed an alternative surgery that wouldn’t leave a scar, a suggestion that didn’t go over too well with Alex.