With 18 seasons and over 300 episodes, Grey's Anatomy has a lot of side characters. Meredith and the other main doctors interact with tons of different people over the seasons, from romantic partners to co-workers, patients, and relatives. Something dramatic is always going on, and while many minor characters appear briefly, many of them stand out as fans enjoy watching them.
From Izzie and Alex's major love interests to some of Meredith's family members, there are many side characters on this hospital drama who contribute to the main plot and feel very significant.
Denny Duquette
When looking at the most unrealistic Grey's Anatomy plotlines, it's hard not to think of when Izzie falls in love with her patient Denny and cuts his LVAD wire so she can attempt to save him. Izzie not only messes up professionally but also thinks that she's sleeping with Denny's ghost.
While Denny is only in a few episodes of the series, he's part of one of the most memorable and recognizable storylines, making him an incredibly significant character. He also impacts Izzie in many ways, making her realize that she actually has cancer.
Dr. Will Thorpe
Will is one of Meredith's love interests but could arguably be her most significant one. While Meredith's relationship wtih DeLuca is important, Will is the person who Meredith thinks about dating after Derek's death, which makes her wonder if she can ever love anyone again.
While Will's time on the show doesn't last, it's easy to picture him becoming a major character. He and Meredith do have a connection and while it makes sense that she's just not ready yet, fans would have loved for them to date longer.
Adele Webber
Adele's story on Grey's Anatomy is tragic and heartbreaking, as she has Alzheimer's and also a miscarriage. It's also sad to think about all the time that Richard spends having an affair with Meredith's mother Ellis.
When Adele dies of a heart attack, it's a big moment on the series that suggests that she's not just a side character. Richard has to come to terms with his affair and how he has let Adele down, and he feels guilty for disappointing her, emotions that he will have to work through for a long time.
Ben Warren
When looking back on the best Bailey episodes of Grey's Anatomy, some of her most interesting storylines have to do with her husband Ben.
Bailey has to suspend Ben when he performs surgery when he isn't supposed to, which hurts their romance and upsets both of them. Since Ben has such a big influence on Bailey, helping her believe in love again and then making her realize that their relationship has some flaws, he could be a major character.
Thatcher Grey
While Meredith's father Thatcher doesn't appear in enough episodes to be considered a main character, he's definitely someone who influences how Meredith thinks and acts.
Meredith never trusts people who she doesn't know well and she can't just open up to anyone, something that she has always told herself because Thatcher has never shown that he wanted a relationship with her. Thatcher becomes even more crucial to the main plot when Meredith gets to know Lexie and learns that Lexie and Thatcher have an enviable daughter/father bond.
Megan Hunt
Fans learn a lot about Grey's Anatomy character Nathan Riggs, including the fact that he was engaged to Owen's sister Megan, who disappeared. When Megan shows up alive in season 13, this changes everything, making her feel like more than just a side character.
Owen is happy and emotional about seeing his sister again and Nathan's new relationship with Meredith is complicated by realizing that of course he wants to be with Megan again. When Nathan leaves to be with Megan and raise Farouk, Meredith has to move on, which is tough since she had just opened herself up to maybe finding love again.
Joe
Of all the minor characters who are often hanging out in the background, the bartender Joe is key to the setting of Grey's Anatomy.
Meredith and her co-workers spend a lot of time drinking at his bar, and it's where they think about what's going on in their lives and try to work through their problems. Fans might not know a lot about Joe, but when he goes fishing with some other characters, Joe talks about his relationship and he seems like a very kind and caring person.
Ava/Rebecca Pope
Alex takes care of Rebecca after she gets into a terrible accident and comes into the hospital. He learns more about her tough story and realizes that her recovery will be incredibly long and difficult.
Rebecca and Alex have a sad relationship as he falls for her while knowing that she's married and that things are complicated. When they try to be together, Alex realizes that Rebecca is struggling and he is there to help her out. Rebecca is one of Alex's most important love interests besides Jo and Izzie.
Penny Blake
Penny's worst Grey's Anatomy moments make her tough to like, but even though she's not the most sympathetic character, she does feel like she could be a main one.
From Penny's role in Derek's death to her romance with Callie, Penny impacts the other characters in many ways. It's interesting seeing how Meredith feels about Penny joining the team at the hospital, and while it's not always possible to love Penny, it's always dramatic watching this character.
Ellis Grey
As the side character who has the most influence on Meredith, Ellis is often the reason why Meredith acts the way that she does.
Ellis influences Meredith to become an amazing surgeon and also makes her think that she can't open her heart up to people. As the show progresses, Meredith becomes closer to different people, realizing that she can be tough while also having good friendships and relationships. Meredith can never forget the sadness that she felt as a child and Ellis always haunts her.