15 Celebs You Forgot Were On Grey's Anatomy

When Grey's Anatomy aired its first episodes, it was an instant hit. Patrick Dempsey quickly became known as "McDreamy" and you couldn't imagine the world without Meredith and Derek together. The show has had some of the most memorable OMG moments from Cristina being left at the alter to Dr. Shepherd's incredibly shocking (and disappointing) death. Now in its 13th season, we have witnessed more farewells, hook-ups, and affairs between staff members than any real hospital has seen. Because of the unique stories and characters portrayed, the show continues to remain a success as it evolves over time.

But aside from our favorite characters, there were also many guest stars that contributed to the drama in each episode. A large number of celebrities have made short appearances which you probably didn't recognize at the time. Few were already Hollywood veterans while some were just starting their acting careers. Let's take a glance at 15 famous stars who have checked in to Seattle Grace Hospital.

15 Abigail Breslin

Famous child star Abigail Breslin has been acting since the age of 3. She received high praise for her breakthrough role in the 2006 film Little Miss Sunshine, which earned her multiple award nominations including an Oscar nod for Best Supporting Actress. Being one of the youngest celebrities to be nominated in that category, her rise to fame was inevitable. That same year, she guest starred as a young foster child on Grey's Anatomy with major bruises to her leg and arm. In the scene, Dr. Karev noticed staples that were bolted into one of her cuts and then immediately assumed that she was abused by her foster parents. She tries to reassure him that they have never harmed her, but Karev suggested other solutions. In order to convince him, she forcefully pulls out the staples one by one and informs him that she has "super powers" which allows her to not feel pain. What a role for a 7-year old! Ultimately it was concluded that she had an extremely rare condition called CIPA (congenital insensitivity to pain with anhidrosis). Abigail played out quite a memorable scene that we think should've earned her an Emmy.

14 Demi Lovato

Following her Disney stint, Demi Lovato took her acting skills to the next level by playing a mentally damaged patient diagnosed with schizophrenia. Her parents were so concerned that they wanted to send her to a psych ward. Frantically she decides to almost stab herself in front of all the doctors, but Dr. Karev, being the nice guy he is, comforts her and assures that he will help any way he can. Demi nailed her role as she repeatedly whispers "I'm not crazy, I'm not crazy." After several exams by Dr. Robbins and Dr. Shepherd with no definitive results, they were convinced that she's just deranged; however, Karev still thinks otherwise. Due to his determination (and shall we add his experience with "crazy" girls), we can safely trust his judgment here! Karev then performs his own tests on Demi where he finds a hole in the bone of her ear causing unwanted noises heard within her body. You are a wonder, Alex!

13 Scott Foley

Before we all knew him as Olivia Pope's sideman on Scandal, Scott Foley played Henry Burton, an uninsured patient who entered Seattle Grace with multiple health issues. He became the new Denny Duquette with a recurring role that got America quickly attached to his character. Although he was in need of surgery, he couldn't proceed with any procedures having no medical coverage. Dr. Altman, saddened by this, offered to marry him so he could be covered under her health plan. Aww, let's label this #uniqueproposals! Unfortunately, Teddy's nice gesture led to some added drama as she continued to date other men during their so-called marriage. Upset that she was seeing someone else, Henry confessed his love for her in anger.

She eventually falls for him and they move in together, marking them as one of our favorite marriages on the show. Nevertheless, all guest stars must face an end as we watched the most heart-breaking surgery failure of all time. Teddy came home to find Henry coughing up blood and rushed him to the hospital. But as his heart could not take the excessive bleeding, he passed away. To this day, we are still in denial that there is no more Henry. Why do you do this to us, Shonda!

12 Josh Malina

Another Scandal star! Josh Malina played Seth Hammer, the husband of a very confused patient Lauren who experienced stomach pain. Confused indeed, she self-diagnosed herself with stomach cancer because… get this… the Internet said so. Yes, we think this is strange too. She admitted to Dr. Karev that she also thought a staph infection occurred, so she ordered antibiotics hoping to cure it. Seth is completely shocked and disappointed as they learn it was just a pimple! Because the antibiotics she took completely erased the good bacteria in her body, she now has Clostridium difficile which can cause an out-of-control inflammation of the colon if not treated. Karev suggests that they perform fecal transplant where stool is transferred from a donor to the patient, and of course Seth is the most suitable to donate his number 2 since they already share germs on a daily basis. They argue back and forth before finally moving forward with the transplant during which he chose not to see. We feel you, Josh Malina, we feel you.

11 Katie Lowes

Wait… Quinn? Ok, we're starting to see the trend here from Shonda Rhimes. Prior to her status as one of Olivia Pope's gladiators on Scandal, Katie Lowes had a very minor part in the final episode of Season 7 in Grey's Anatomy. And when we say minor, we mean she didn't even have a name on the show. According to IMDb, she simply played "Blood Donor". To assess her qualifications to offer blood, Cristina asked Katie's character some mandatory questions including the possibility of being pregnant. Katie's character had no idea if she was carrying a baby and cannot remember when her last period took place. After more questions regarding hormonal changes, Cristina actually ignores her responses. This happens to be the same episode when Teddy and Henry (Scott Foley's character) shared their first kiss.

Despite having no name on the show, Shonda also cast her in Private Practice, the spinoff of Grey's Anatomy (as if Grey's fans don't already know Private Practice). Obviously, having a small gig on one of Shonda's shows gives you a higher chance to land something big in the future. Certainly, for Katie, Scott Foley, and Josh Malina, that was the case!

10 Seth Green

One of America's favorite 90's stars known for his roles in Can't Hardly Wait and Austin Powers, Seth Green guest starred in a two-part episode in the fourth season. As Nick Hanscrom, he was a suffering patient with an exposed artery caused from a tumor removal. Hardly any skin had covered his wound, which worried the doctors of a possible rupture. While Mark Sloan was his attending physician, Lexie was at his bedside for most of the episode. They flirt and share some jokes between one another, but unfortunately his laughing caused his artery to suddenly split open with blood splashed onto her body. She immediately tries to stop the bleeding and quickly calls for Dr. Sloan. Despite his condition, Seth's character continues to chat it up with Lexie and admits that he's in love with her although he has a girlfriend. Talk about instant chemistry! With no vein for a blood transfusion, an abrupt stroke, and a closed OR, he was only suffering more and more. Sloan attempted to fix his carotid even without access to the OR, but he was eventually pronounced dead.

9 Sarah Paulson

Sarah Paulson is definitely a Hollywood veteran famous for her acting chops in Deadwood, American Horror Story, and most recently an Emmy Award-winning performance in The People vs. OJ. She is as talented as they come, and without a doubt, her guest role in Grey's was no less than perfect.

She played a young Ellis Grey in a flashback episode that depicted her medical work at Seattle Grace long before facing Alzheimer's. In this Season 6 event, the young Richard Webber explained how he and Ellis discovered an unusual fungus on a patient they helped in 1982. They asked multiple questions to get to the root of the condition including possible trips overseas and close interactions with animals. Ultimately, they presumed the issue could be GRID (Gay-Related Immune Deficiency), today known as AIDS. Additionally, while in the midst of the case, details of Ellis and Richard's affair were uncovered as she insisted that Richard leave his wife for her. At the time, Meredith was just a toddler. Imagine the chief as stepdad to Meredith!

8 Christina Ricci

If you watched the show from Day 1, you probably remember the iconic episode of the man with a bomb inside his chest in Season 2. Christina Ricci gives a noteworthy performance as Hannah, an EMT whose hand is inside the patient to keep the bomb from going off. Oh, and keep in mind the bomb was homemade… Only on Grey's Anatomy you will watch a crazy incident like this! For hours she is stuck in the OR with the patient and waits for Dr. Burke to scrub in. As he prepares to perform a procedure that would remove Hannah from the patient, Karev rushes into the OR and cautions Burke of Hannah's likelihood to die because the bomb is unstable. Burke calls for code black and immediately sends a bomb squad to take care of the situation instead. Still panicked, Hannah just couldn't hold on any longer and lets go of the bomb. Eek! While she runs away, everyone ducked for their lives and Meredith ends up taking Hannah's place holding the bomb herself. If you were like the rest of America, this certainly had you on the edge of your seats.

7 Kyle Chandler

Well-known for his role in Friday Night Lights, Kyle Chandler actually shows up in the same episode as Christina Ricci, playing Dylan Young who's the temperamental leader of the bomb squad. While the entire unit except the OR has evacuated, Dr. Shepherd's operating room chose to remain on the floor. Dylan becomes frustrated as several of the staff wanted to stay and implies that he got authorization from the chief to evacuate everyone. After Meredith took Hannah's (Christina Ricci) place in holding the bomb inside the patient, Dylan and Burke carefully plan on a solution. After slowly transferring Meredith to a safer side of the hospital floor in order to avoid the entire building from blowing up (again, we are at the edge of our seats here), they begin to finally remove the bomb and Meredith gently hands it over to Dylan. Then right when you thought everything went smoothly, the bomb explodes killing Dylan as he walks away holding it. Let's take a breather as we reminisce on this roller coaster episode.

Kyle did return to the show in Season 3 but as an illusion in Meredith's mind.

6 Kevin Rahm

Kevin Rahm has portrayed characters in a multitude of great shows, including Desperate Housewives, Mad Men, and most recently Lethal Weapon. As a psych patient named Mr. Duff on Grey's, he was checked in to the hospital for calling himself a psychic. He informs the staff that he talks to dead people and his family thought he was dangerous for this. After having several seizures in front of the doctors, he claimed that they were just visions of the future. Sure of his "visions", he predicted that a patient on another floor - the fourth floor to be exact - would not stay alive. In an instant, a code blue had been called for (yes, you guessed it) the fourth floor. How surreal! Cristina was originally assigned to Mr. Duff, but after he foresaw that she was pregnant (remember her secret attempt to abort Burke's child?), she requested to be off the case. Following surgery that was supposed to fix a brain arteriovenous malformation, he said his visions were still occurring. Hey, perhaps he really could see the future. We wonder if he knew that half of the cast members would somehow die.

5 Neve Campbell

The original "Scream" queen Neve Campbell starred as one of Derek's four sisters in Season 9. Known for her 90's role in Party of Five and most recently House of Cards, Neve's character Lizzie Shepherd was also a doctor. Can we say their parents must be proud? After Derek's left hand was severely injured in a plane crash, which also led to the shocking deaths of Mark and Lexie, Lizzie visited the hospital to ensure he gets a nerve transplant surgery. Derek's hand was so damaged it lost control of any sensation and movement to the fingers. Lizzie offered to donate a nerve from her limbs to help him regain momentum. Additionally, the episode highlighted Meredith's lack of desire to bond with Lizzie as we all know that she hasn't experienced the best of family moments (for example: mother having an affair, estranged father, and long-lost half sister just to name a few). But in the end, Meredith opens up and even shows an ultrasound picture of her and Derek's new baby.

4 Mandy Moore

It is evident that Mandy Moore has portrayed some likable characters in her career, including the oh-so-popular Nicholas Sparks love story A Walk To Remember. In one of the most traumatic moments in the show, Mandy Moore starred as Mary Portman who ended up trapped in the hospital during a shooting. She stayed in a room with Dr. Bailey during the unfortunate event. Bailey advised her to play dead so the shooter wouldn't target her when he walked into their room. Although both ladies were not hurt, the shooter did aim at Charles Percy.

Months after the shooting, a camera crew followed Mary and her husband around for a mini docu-series where they filmed her returning to the hospital. Bailey performed a successful surgery, but somehow Mary did not wake up and was later taken off life support. Because she grew quite fond of Mary, Bailey wanted to help with her autopsy although no result was found. It is rare to watch the usually tough surgeon develop deep connections with her patients, but we absolutely loved this BFF pairing.

3 Keke Palmer

True Jackson, VP star Keke Palmer has come a long way from her Nickelodeon days. In Season 10, she took on a small role of a 17-year old troubled girl Sheryll Jeffries who ran away from home and got pregnant. She at first arrived at the hospital in hopes of joining Cristina's surgical trial but finds out that she does not meet the qualifications. While speaking with Dr. Shane Ross, Sheryll's water broke and he immediately sends her to the Labor & Delivery unit. Though you would think that in any normal labor getting the baby out would be the top focus, but she continues to ask to talk to Cristina. As her contractions get more painful, Cristina does come meet with Sheryll but still rejects her from the trial. Eventually, her baby daughter was delivered six weeks premature and Shane suggests that she be put on a transplant list.

2 Sarah Chalke

Being on the other side of the hospital bed must've been a change for Sarah Chalke, who is famous for playing a doctor on Scrubs. Guest starring as Casey Hedges in Season 9, she plays a concerned mother making several visits to the hospital with her son because she feels he had been misdiagnosed. Explaining to Dr. Jo Wilson that her son's temperature had been over 103 for more than a week, she was sure that it wasn't just a virus. Upset that no one believed her and being dismissed from other hospitals, she returned again with her son and demanded a different doctor besides Jo. Meredith overheard their conversation, and of course being the empathetic person we love, she told Jo to admit Casey's son.

While it took several tests to find a diagnosis other than strep, Meredith realized Casey's son had Kawasaki disease which causes inflammation in the blood vessels usually affecting children. The doctors got to work right away to prevent permanent heart damage. As the saying goes, a mother's instinct is always right.

1 Chris O'Donnell

If there was ever a common theme in most of Shondaland TV shows, it would be the occasional love triangle. NCIS star Chris O'Donnell played a widowed veterinarian who treated Meredith's dog after she had broken up with Derek. As Dr. Finn Dandridge, he starred in nine episodes first appearing in Season 2 where the battle for Meredith's love began. Initially hesitant to go on a date with him, Meredith agreed to several meet-ups with Finn, sooner or later realizing what a kind, heartfelt gentleman he was. I mean, come on… breakfast in bed, bringing desserts to the hospital, and let's not forget that he birthed a horse! Is there a bigger "aww" moment?

Despite Finn's continued devotion, Meredith just couldn't let go of Derek. In his last episode, Meredith tells him that Derek is "the one", ending our chances to see the charming vet again. Whether you were Team McDreamy or Team McVet, you couldn't deny Finn's romantic gestures and affection for Meredith.