Grey's Anatomy normally sheds some of its characters each year, with reasons for departure ranging from sudden death to resignations to the pursuit of fresh dreams. In Season 17, Jackson Avery and Andrew DeLuca exited the show, and fans were happy, as both characters had been around for a couple of seasons and saw their storylines wrapped up perfectly.
However, not everyone enjoys longevity. There are those that left prematurely, having only appeared in a few episodes or seasons. A number of the early exits were painful to fans because the characters in question were either showing much promise, had great personalities, or were part of riveting narratives.
George O'Malley
George, a surgical resident at Seattle Grace Hospital, saw his time on the show come to a brutal end when he was hit by a bus while trying to save a woman. At the time of his death, George had only been around for 6 seasons.
George's departure was a big blow to the show because he was one of the funniest characters. He once laid out a couple of the best "Mc" labels on Grey's Anatomy, stating: "McDreamy was doing the McNasty with McHottie? That McBastard!" In addition to his humor, George was part of great relationship storylines that had him fall for Izzie, Callie, and even Meredith. He was bound to pair up with more interesting characters if he'd stayed much longer.
Denny Duquette
Denny, one of the most memorable patients on the show, was only around for 2 seasons. During this time, he was included in key story arcs such as a relationship with Izzie and the LVAD wire incident.
Denny was a romantic, evident from how he woke up from a coma and made proposing his first priority, before coding again. The show thrives on romance and much more would have come out of Denny and Izzie coupling up. And after his struggles with viral cardiomyopathy as well as difficulty getting a transplant, fans would have been overjoyed to see him come out triumphant over his woes.
Erica Hahn
Erica wasn't always friendly with her colleagues but she was a great surgeon with a good bedside manner. She also had a tumultuous relationship with Callie that ended with an argument about whether to report Izzie over the LVAD wire incident. Erica's weird exit involved her walking away on the parking lot after only 3 seasons of actress Brooke Smith's strong performances.
The cardiothoracic surgeon's sudden departure had an unsatisfactory feel to it since didn't make much sense for a doctor who really loved her job to quit over a minor argument with a partner. If other issues affected her decision, they ought to have been explained first. Her romance with Callie was also only starting to get interesting and fans would have loved to see whether the two would have sorted their difference in ideology.
Nathan Riggs
The cardiothoracic surgeon was part of an interesting love triangle involving Meredith, and Megan. After dating Meredith for a while, his long-lost fiance Megan reappeared, and without thinking twice, he rekindled his love with her. Nathan had only been introduced in Season 12 but by Season 14, he was gone, counting himself among the most notable doctor resignations on the medical drama.
It was unlike Nathan to not fight for Meredith, and to quit his lucrative job so quickly. Someone needed to challenge Meredith's tendency to refrain from loving anyone else as deeply as she loved Derek. Nathan would have been a perfect candidate for that, showing Meredith that he was equally as good. After all, Megan was willing to let him be with the lead character.
Henry Burton
Henry lacked the insurance needed to cover his Von-Hippel-Lindau syndrome surgery. After failing to get his girlfriend to marry him so that he could use her insurance, Teddy surprisingly offered to marry him so that he could use hers. Sadly, the good gesture went to waste. After making only 15 appearances across seasons 7 & 8, Henry died.
Henry's departure was hard to digest because he had made significant progress before his death. He was becoming his bubbly self once again, playing softball with the Seattle Grace Mercy West doctors, and even revealing his plans to go to medical school. It would have been a great example of people overcoming life's challenges if Henry had morphed from an almost dying patient to a doctor. Fans would also have loved to see whether he'd repay Teddy for her sacrifice or whether he'd become unappreciative.
Preston Burke
Preston Burke will always be remembered as the man who left Cristina at the altar and the man who also took her away from Meredith. Despite his flaws, Burke was a great surgeon and businessman who managed to win the Harper Avery Award before founding the Klausman Institute for Medical Research. Unfortunately, he only appeared in 3 seasons.
While Burke's decision to leave Seattle in order to manage his own hospital made sense, his relationship with Cristina needed to be spread out across a few more seasons for purposes of closure. The aftermath and consequences of the altar moment were never properly explored, and this made Burke an irredeemable villain yet he might have had genuine reasons to walk away.
Susan Grey
In a show full of cold, calculating, and mean characters, Meredith's stepmother Susan Grey stood out for her good-heartedness. She offered herself to Meredith as a source of solace when Ellis died. Meredith ignored her at first but the two began growing closer only for Susan to die after developing complications from hiccups. She had only managed 6 appearances across seasons 2 & 3.
Meredith never had a good parent-child relationship with either Thatcher or Ellis so there was hope that Susan would fill that void. For that to happen, she needed to interact with Meredith much longer. Her persistence and patience while attempting to create a bond with her step-daughter had already made her one of the most likable members of Meredith's family. There's no doubt that she would have helped improve Meredith's relationship with Thatcher too.
Dylan Young
One of the most shocking things Meredith ever did was placing her hands on an explosive that was lodged inside a patient named James Carlson. It was courageous but unwise. The explosive detonated seconds after she had handed it over to Dylan, a member of the Seattle Police Department Bomb Squad.
Though Dylan only lasted two episodes, he had strongly showcased his traits of courage and daredevilry. There was the desire to see what more he would offer. Better storylines could have involved him sustaining injuries and spending time at the hospital before recovering or Meredith developing a friendship (or even love) with him after he saved her life.
Shane Ross
The hardworking and charming Shane endeared himself to Derek, April, and even the tough Cristina, who briefly became romantically involved with him. His likability earned him nicknames such as "Sharky" and "Tardy Marky." Surprisingly, as events were hinting at him becoming one of the main characters, he followed Cristina to Switzerland. He only lasted 2 seasons.
Shane's charming nature meant he could have easily been included in another romance storyline very easily. He was doing himself a disservice by following Cristina as she had made it clear she had no plans of dating him. Shane's promising future meant he was better off in Seattle. He had more friends there. He also idolized Derek hence staying closer to him would have made more sense.
Ellis Grey
Ellis was no good mother to Meredith but she was a superstar surgeon, something that qualified her as a compelling character in a show that's about medicine. After only appearing for the first 3 seasons, she succumbed to Alzheimer's disease.
The word famous surgeon was extremely arrogant, selfish, and overbearing. These traits made her the perfect villain. For this reason, her long-term presence would have been beneficial. Grey's Anatomy has always been short of compelling antagonists and Ellis ought to have been pitted against the protagonist, who was her own daughter, for many more seasons to come before being killed off.