Content Warning: the following article contains discussions of medical themes.

Considering that Grey's Anatomy is the longest-running medical drama on American television, it's not surprising that the show has managed to draw in a multitude of actors. From Academy Award winners to Grammy nominees, the viewers have seen several iconic stars make a huge impact on the show as they have participated in the biggest storylines (such as the hospital bomb) or had profound character arcs.

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While it is always interesting to see a fan favorite celebrity make a rare appearance on the show or a few cameos, there have been a few Grey's Anatomy guest stars that left a truly memorable impression. Hopefully, this plethora of memorable celebrity guest stars will continue to increase as the Grey's Anatomy writers are still coming up with unique and creative storylines to keep everyone entertained.

Updated on January 9th, 2022 by Kayleigh Banks: With Scott Speedman's Nick Marsh reprising his role as Meredith's love interest, E.R Fightmaster's Kai Bartley striking up a romance with Amelia, and Peter Gallagher's David Hamilton trying to get Meredith to leave Seattle, it's safe to say that many Grey's Anatomy guest stars have had a major impact on the show so far.

While the writers might have intended for these celebrities to only appear in several episodes, the viewers might begin to see more of them since their characters have proven to be a hit with the Grey's Anatomy fans. It'll be interesting to see their character's backgrounds explored in more depth as it will not only allow the viewers to get to know them more, but it could also create new characters and new opportunities for other stars to make some cameo appearances too.

Geena Davis

Nicole Herman and Arizona Robbins looking at a patient in Grey's Anatomy

With the series having been on the air for nearly twenty years, the casting directors have managed to draw in some impressive talent, including a couple of Academy Award winners. One of these stars includes Geena Davis, who appeared in 13 episodes between seasons 11 and 14 as Dr. Nicole Herman.

While Nicole Herman wasn't exactly the most likable character to appear on the show due to her blunt and controlling behavior, Grey's Anatomy fans did love the unexpected friendship that blossomed between her and Arizona. Not only did she help to improve Arizona's medical skills but she also helped her to achieve her ambitions too.

Keke Palmer

An image of Keke Palmer's character, Sheryll Jefferies, in Grey's Anatomy

Featuring in season 10's "We Gotta Get Out Of Here," Keke Palmer was another A-list celebrity to make an appearance on Grey's Anatomy. She was cast as Sheryll Jefferies, a young pregnant teenager, who came to Grey-Sloan Memorial to try and get on Cristina's trial so she could treat her Hypoplastic Left Heart Syndrome. However, problems soon arise when she goes into labor.

Although her storyline wasn't the most memorablePalmer has gone on to have a very successful career since her appearance in Grey's Anatomy. Not only had she appeared in Berlin Station but she also received a Primetime Emmy for her role in Turnt Up with the Taylors ("Oustanding Actress in a Short Form Comedy or Drama Series"). 

Abigail Breslin

An image of Abigail Breslin's character, Megan, in Grey's Anatomy

Grey's Anatomy is known to have helped to propel many child stars into fame further. However, if there was one performance that stood out to fans, it would have been Little Miss Sunshine actor Abigail Breslin's.

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Appearing in the season 3 episode "Sometimes a Fantasy," the Academy Award nominee played Megan Clover, a young girl who believed she had superpowers when she found herself insensitive to pain. However, the case appeared to be more complex than that and created some interesting character development for Alex, who continued to show his caring and nurturing side (which might have foreshadowed his career in the pediatric department).

John Cho

An image of John Cho in Grey's Anatomy

Before he was helping Captain Kirk to navigate the USS Enterprise across space, John Cho had previously made a guest appearance on Grey's Anatomy as Dr. Marshall Stone. Only featuring for one episode, the viewers discovered that Marshall had been in a car accident after he fell asleep at the wheel ("Damage Case").

Sadly, this ended up having major consequences as a young woman ended up dying in the aftermath of the crash. While the writers seemed satisfied with the ending that they had created for Cho's character, many fans were a bit disappointed that he didn't get a long-term deal since he could have easily fit in with the interns. It would have also been interesting to see how he coped in the aftermath of his accident since he had a lot of guilt and remorse over his actions.

Elisabeth Moss

An image of Elisabeth Moss's character, Nina Rogers, in Grey's Anatomy

Although many people know Elisabeth Moss best for her role as June Osborne in The Handmaid's Tale and Peggy Olson in Mad Men, some fans might have forgotten that the two-time Emmy award-winning actor also appeared on Grey's Anatomy for one episode.

Featuring in season 3's "My Favorite Mistake," Moss played Nina Rogerson, the daughter of a patient who was diagnosed with Fibrodysplasia ossificans progressiva (FOP). While many family members only get a few lines, Moss was actually an integral part of the storyline as the show explored her relationship with her mother in-depth and what her experience was like as her mother's carer.

Loretta Devine

Adele Webber looking concerned in Grey's Anatomy

Television veteran Loretta Devine played the role of Richard Webber's wife, Adele, for 22 episodes (and over the course of seven seasons). For her performance in the show's sixth season, she won the Primetime Emmy Award for "Outstanding Guest Actress in a Drama Series." She received a second nomination the following year.

Adele had certainly been a fan favorite with the fans as the viewers loved her no-nonsense attitude. However, this wasn't the role that many remember her for. Devine first gained prominence as Lorell in the original Broadway production of Dreamgirls. She went on to appear in numerous television shows over the years, like A Different WorldThe PJs, and Boston Public.

Demi Lovato

An image of Demi Lovato on Grey's Anatomy

Back in 2010,  Lovato appeared in the episode titled "Shiny Happy People." Lovato played Hayley May, a young teen who had recently been misdiagnosed with schizophrenia. Lovato's performance was generally well-received, although most of the praise went for the episode's other major guest star, television icon Marion Ross.

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Lovato went on to have a successful musical career, with only sporadic appearances in both film and television. For their performance in the episode, she won a People's Choice Award.

Mandy Moore

An image of Mary smiling at Bailey in Grey's Anatomy

Mandy Moore rose to prominence in the late '90s thanks to her single "Candy." She later starred in a series of successful teen movies like The Princess DiariesA Walk to Remember, and Saved!. Starting in 2016, Moore found critical acclaim thanks to her role as Rebecca Pearson in This is Us, for which she received nominations for the Primetime Emmy Award and the Golden Globe.

Moore played Mary Portman in 4 episodes of Grey's Anatomy's sixth and seventh seasons. She memorably gets trapped with Bailey during a hospital shooting and later returns to get surgery, but doesn't find a happy ending - much to the disappointment of fans.

Christina Ricci

An image of Hannah looking concerned in Grey's Anatomy

One of the most famous child stars of the early '90s. Christina Ricci went on to successfully transition into adult roles. She starred in the forgotten dark rom-com, The Opposite of Sex - for which she received a Golden Globe nomination in 1999 - and had leading roles in films like Sleepy HollowMonster, and Speed Racer.

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Ricci is one of Grey's most memorable guest stars. She played Hannah, a young paramedic with her hand stuck inside a man's chest cavity, holding a piece of unexploded ammunition. Ricci received critical acclaim for her performance, as well as an Emmy nomination for "Outstanding Guest Actress." Although she hasn't been since this episode aired, fans would love it if they got an update as Hannah was quite likable and engaging.

Leslie Odom Jr.

P.J. Walling rests on his bed after donating his kidney in Grey's Anatomy

Long before Leslie Odom Jr. rose to prominence, and won a Tony Award for Hamilton, he guest-starred in Grey's Anatomy's fifth season, playing P.J. Walling, who was a man that was willing to donate his kidney in exchange for $10,000. Although a minor role, fans got a glimpse of Odom Jr's talents as he provided a raw and emotional performance when his character realized how ill his father was.

Odom Jr.'s career took off after his starring role in Hamilton. This year, he received a plethora of nominations. including for the Golden Globes, SAG, BAFTA, and Academy Awards thanks to his performance as Sam Cooke in Regina King's directorial debut, One Night in Miami.

Sarah Paulson

Sarah Paulson as young Ellis Grey in Grey's Anatomy

Long before she became a staple of the Ryan Murphy-verse, Sarah Paulson played the role of a young Ellis Grey in the sixth season episode "The Time Warp." The plot features several flashbacks, which allowed viewers to see what the dynamic between her and Richard was like and how their affair began. Although she was only in the show for this one episode, many fans would agree that Paulson captured Ellis' character perfectly as her lines were delivered coldly and bluntly.

Paulson's name already was familiar to tv viewers by the time she guest-starred in Grey's, but her journey to critical acclaim had yet to begin. The following year she received an Emmy nomination for Game Change, the first of seven. She finally won the statuette in 2016 for her role as Marcia Clark in The People v. O.J. Simpson.

Alyssa Milano & Holly Marie Combs

Richard tells Haylee and Heidi Peterson to stop fighting

Piper and Phoebe Halliwell returned to television during Grey's sixteenth season. The episode - aptly titled "Reunited" - features Holly Marie Combs and Alyssa Milano as sisters trying to decide if they should or should not take their third sister off life support.

The two actresses starred as two-thirds of the Charmed ones in The WB's Charmed and proved that their chemistry was still intact as the lines between them flowed well and naturally. Before that, Milano was best-known for her roles in Who's the Boss and Melrose Place, while Combs made a name for herself thanks to Picket Fences.

Tessa Thompson

Tessa Thompson had her big break in 2015 when she played the role of Blanca Taylor in Creed. Soon after, she received the coveted and pivotal role of Valkyrie in Thor: Ragnarok, thus becoming part of the Marvel Cinematic Universe.

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Nearly ten years before that, though, Thompson played the role of Camille Travis, Richard Webber's niece. Diagnosed with ovarian cancer at fourteen, she's unable to attend her prom and the staff at Seattle Grace throws one for her at the facilities.

Kyle Chandler

Dylan Young briefs the Seattle Grace staff about the bomb situation

Shortly before Kyle Chandler received the role of Coach Taylor in Friday Night Lights, he first appeared in two Grey's episodes, "It's the End of the World" and "As We Know It." He played Dylan Young, a bomb squad leader who meets an untimely and shocking ending.

For his role in Grey's, Chandler received his first Emmy nomination. He'd go on to win the statuette for Friday Night Light's final season. He keeps steadily working in both film and television, featuring in the blockbuster Godzilla vs. Kong and Mayor of Kingstown.

Millie Bobby Brown

Ruby and Owen talking at Seattle Grace's waiting room

Godzilla star Millie Bobby Brown received instant critical acclaim thanks to her role in Stranger Things. For her performance as Eleven, Brown received two consecutive Emmy nominations, although she failed to win any of them.

Before her breakthrough in the Netflix hit, Brown played Ruby in season eleven of Grey's. After a powerful earthquake hurts her mother, Ruby needs to care for her, receiving indications from Seattle Grace's medical staff. The two eventually get to the hospital, where the mother survives her surgery.

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