Denny Duquette, the doomed patient who fell in love with Izzie Stevens in Season 2, died in that season's final episode after suffering a post-heart transplant stroke. He subsequently appeared in ghost form during Meredith's near-drowning and for his and Izzie's truly mind boggling brain tumor-induced ghost sex storyline.
Likelihood of returning (again): Not very good. With Izzie out of the picture and Morgan occupied playing Negan on The Walking Dead, we're guessing Denny has checked out of the hospital permanently.
Oh, Finn. The veterinarian introduced in Season 2 as a potential love interest for Meredith was cute and charming, but couldn't hold a candle to Meredith's ultimate bae, Derek. She let him down easy at the beginning of Season 3.
Likelihood of returning: Slim, but we would fully support Meredith and Finn rekindling their romance now that she's lost both Derek and Riggs.
The brilliant surgeon Ellis Grey, who was Meredith and Maggie's mother and Richard's former lover, succumbed to Alzheimer's in Season 3, but is still occasionally seen in flashbacks.
Likelihood of returning: Very good. So much of Meredith's character development is rooted in Ellis flashbacks that we find it hard to believe the writers would drop this device permanently.
At least Addison got kind of a happy ending when she left Grey's at the end of Season 3. She traded Seattle for Los Angeles and her own spin-off, Private Practice, making sporadic returns to the mothership through Season 8.
Likelihood of returning: Slim, but possible. Walsh has said she's open to returning to the series -- although, if she didn't even come back for her own brother's funeral, we're hard-pressed to think of something that would bring Addison back to Seattle.
Preston Burke, the extraordinary, surly head of cardiothoracic surgery at Seattle Grace, left his fiancee Cristina Yang, and the show, in the Season 3 finale. (In real life, Washington was fired after using an anti-gay slur in reference to his co-star T.R. Knight.) Burke reappeared in Season 10, when Cristina accepted a job at his medical research facility in Zurich.
Likelihood of returning: Even after Washington's ignominious initial exit, he was invited back for that Season 10 episode, so anything is possible we guess!
A pregnant patient who was brought to Grey Sloan after the ferry accident in Season 3 with complete memory loss, Rebecca (aka Jane Doe, aka "Ava") developed a close bond with Alex Karev. Unfortunately -- or fortunately, depending on how you look at it -- she eventually regained her memory, only to realize that she was unhappily married. Upon learning that Rebecca had borderline personality disorder (after she had stalked him, faked a pregnancy and attempted to slit her wrists), Alex had her committed to a psychiatric facility at the end of Season 4.
Likelihood of returning: Basically none.
Erica Hahn was initially brought to Seattle Grace as an emergency stand-in to perform Denny Duquette's heart surgery after Burke was shot. She later replaced Burke on the staff full-time and developed a romance with Callie, then left the hospital in the early part of Season 5 because she couldn't accept that Callie was bisexual and not strictly a lesbian.
Likelihood of returning: Not gonna happen, especially now that Callie's gone.
Sadie, who was a college friend of Meredith Grey's, had a short-lived stint as an intern at Seattle Grace in Season 5. Her departure came after a number of infractions, including having her fellow interns practice medical procedures on each other and possibly cheating her way into the program in the first place.
Likelihood of returning: Nada. That friendship is ovah.
George "007" O'Malley was one of the O.G. interns until he was tragically killed when he jumped in front of a bus to save a woman's life in the Season 5 finale.
Likelihood of returning: Perhaps in a flashback for the series finale, or -- god forbid -- another ghost storyline.
After a nasty behind-the-scenes feud between Katherine Heigl and the Grey's Anatomy creative team, her character Izzie Stevens was written out of the show midway through Season 6. After discovering her cancer is in remission, Izzie left Seattle to make a fresh start (and officially divorced Alex offscreen a few seasons later).
Likelihood of returning: Heigl has said she's open to the idea of Izzie returning to Grey Sloan, but so far the writing staff hasn't taken the bait.
Charles Percy was a surgical resident who arrived as part of the merger between Seattle Grace and Mercy West hospitals. He died in an elevator after being shot by vengeful gunman Gary Clark, who opened fire in the hospital in the Season 6 finale.
Likelihood of returning: Nope.
Joe was (and is?) the amiable bartender and owner of "Joe's Bar," who served the Grey's doctors much-needed adult beverages after long shifts at the hospital (and witnessed many, many of their drunken hookups). Maybe because the docs are now older and (theoretically) wiser, and have to head home to their families after work instead of the bar, Joe hasn't been seen since Season 7.
Likelihood of returning: Maybe? Joe fans need closure!
Henry came to Grey Sloan as a patient who lacked insurance, and married Dr. Teddy Altman (Kim Raver) so that he could have life-saving surgery. Though their marriage happened for insurance reasons, they later fell in love for real. Sadly, he died on Cristina's (Sandra Oh) operating table in Season 8.
Likelihood of returning: The slimmest of possibilities, maybe in a flashback now that Teddy has returned to Grey Sloan.
Meredith's (first) long-lost half-sister came on the scene in Season 3 as a surgical resident, joining Seattle Grace in the hopes of meeting her mystery sibling. Though she and Meredith initially got off to a rocky start, the sisters grew very close before Lexie was sadly killed in the plane crash at the end of Season 8.
Likelihood of returning: Slim, unless Meredith starts having ghost hallucinations again.
After joining Grey's in its sophomore season, Mark Sloan was killed off at the beginning of Season 9 after he and several of his colleagues were involved in a plane crash. Once he had been unresponsive and in a coma for 30 consecutive days, Mark's life support was removed per his wishes, and he and his on-again-off-again girlfriend Lexie Grey became the namesakes for "Grey Sloan Memorial."
Likelihood of returning: Fans would love to get another glimpse of "McSteamy." Maybe the series finale could be set in Grey's heaven, where the ghosts from the show all reminisce about their plotlines.
Richard Webber's wife passed away in Season 9 after suffering a fatal heart attack post-emergency surgery. She had endured a lengthy battle with Alzheimer's prior to her death that resulted in Richard having to move her into an extended care facility.
Likelihood of returning: Maybe in a flashback, although Richard has firmly moved on with Catherine Avery.
The enthusiastic yet unpopular intern Heather Brooks lasted only a short time at Grey Sloan before she was electrocuted and killed in the wake of the "Superstorm" at the beginning of Season 10.
Likelihood of returning: Nah.
Matthew, the sweet paramedic who was April's fiance, left Grey Sloan midway through Season 10, after Jackson "spoke now" at his almost-wedding to April and broke up their relationship. Who could blame him?
Likelihood of returning: No reason to bring Matthew back, since he was basically just a plot device to bring Japril together.
This one hurt. Cristina Yang -- original Grey's intern, Meredith's Person, and Owen's wife -- left Grey Sloan at the end of Season 10 to take a position as Director of Cardiothoracic Surgery at a medical research facility in Zurich, Switzerland, at the invitation of her former beau, Preston Burke.
Likelihood of returning: Cristina's presence was "implied" at Derek's funeral in Season 13, when a dark-haired actress stood in for Oh and was seen putting her arm around Meredith from the back. Hopefully Oh's schedule will free up at some point, because a Meredith-Cristina reunion dance is probably on every fan's wishlist.
Shane Ross, who was part of the intern group that included Jo and Stephanie, left Grey Sloan at the end of Season 10 as a surgical resident. The reason? He was offered the opportunity of a lifetime (after only a little begging) to join Cristina Yang in her new gig at a medical research facility in Zurich.
Likelihood of returning: If Cristina ever comes back, maybe she'll bring Shane with her? Or maybe Meredith can take a trip to Switzerland in a future episode to visit her BFF.
Head of fetal surgery and Arizona's mentor Dr. Nicole Herman was diagnosed with a brain tumor and only given six months to live. A miracle surgery performed by Amelia removed the tumor but also left Herman blind. No longer able to practice medicine, Herman left midway through Season 11 to live at the Blind Institute.
Likelihood of returning: Probably not, although it could happen.
The ultimate loss for Grey's Anatomy fans was the shocking death of Dr. Derek Shepherd, aka "Dr. McDreamy," aka Mr. Meredith Grey, at the end of Season 11. After tending to victims of a bad car crash on the side of the road, Derek dies from injuries he sustained when his own car was hit by an oncoming semi-truck as he reached to answer his cell phone. Making matters worse, Derek's death was due at least in part to negligence and improper training on the part of the doctors at the hospital where he was taken.
Likelihood of returning: Dempsey motored out of Grey's Anatomy and hasn't looked back since. Although we wouldn't be surprised if he appears in flashback/ghost form for the series finale.
Ramirez shocked fans when she left Grey's Anatomy at the end of Season 12 after more than 10 years playing Callie Torres. After a nasty custody battle with her ex-wife Arizona (Jessica Capshaw), Callie decided to leave Seattle and move to New York with her and Arizona's daughter, Sofia.
Likelihood of returning: Callie will probably be back at some point. She and Arizona share custody of Sofia, after all.
Surgical resident Leah Murphy was fired in Season 10, after her first stint at Grey Sloan (but not before sleeping with and becoming obsessed with Arizona), but she returned in Season 13 after proving that she could be a capable surgeon after all. The character inexplicably did not return for Season 14.
Likelihood of returning (again): God, we hope not.
Minnick came in with a bang (literally, if we're talking about her relationship with Arizona) in Season 13, and quickly made enemies of... well, just about everyone at Grey Sloan, as well as viewers. Once Bailey realized that Minnick's "innovative" methods were causing more harm than good at the hospital, she was fired (offscreen) at the end of Season 13.
Likelihood of returning: Not looking good.
One of the new crop of interns who came to Grey Sloan in Season 11, Isaac is another character who appears to have been dropped ahead of Season 14.
Likelihood of returning: Our money's on no.
Edwards joined the ranks of Grey Sloan in Season 9 and worked her way up to be a surgical resident. But the trauma of getting kidnapped and held at knifepoint by a deranged patient and nearly dying in a hospital inferno at the end of Season 13 proved too much for her. She decided to leave the hospital - and medicine entirely - in the finale, and live life to the fullest after completing her recovery in Texas.
Likelihood of returning: Anything is possible, but highly unlikely.
A blast from Owen's past, the cocky Nathan Riggs joined the ranks of Grey Sloan in Season 12 after working with April during her stint in Jordan. Though he and Meredith struck up a romance, he left at the beginning of Season 14 after his formerly presumed-dead fiancee (and Owen's sister) Megan was discovered alive in Iraq and brought to the United States. Over Owen's objections, the pair moved to Los Angeles to start over.
Likelihood of returning: Maybe? An awkward run-in with Meredith a few months down the line could be a breeding ground for the type of drama Grey's loves.
Owen's sister was thought to be dead after her helicopter crashed in Iraq years earlier, but she was found alive and brought to Grey Sloan at the end of Season 13. After she recovered during the early episodes of Season 14, she headed to California with Nathan and her adopted son, Farouk.
Likelihood of returning: Fairly high. She and Nathan have promised to come visit, and she and Owen have a lot of lost time to make up for.
Dr. Teddy Altman left Grey Sloan (and all the painful memories of her deceased husband, Henry) behind in Season 8 to take a job as Chief at MEDCOM.
Likelihood of returning: Check! She returned to the hospital in Season 14, accompanying Megan Hunt after she was found alive in Iraq.