Grey's Anatomy revolves around the lives of the doctors and patients at Grey Sloan Memorial Hospital. Within the 18 years of showtime, the show has introduced numerous characters. As each goes through their ups and downs, they are shaped by their decisions, experiences and how they behave with others.
As a result, their character arcs are constantly evolving, leaving room to grow. From Alex Karev, who went from a pompous, inconsiderate doctor to one with compassion, to Mark Sloan, a lothario who became an amazing dad, these characters had some of the best character developments on the show.
10 Richard Webber
Richard Webber (James Pickens Jr.) was first introduced as the Chief of Surgery at Seattle Grace Hospital. Not only was his infidelity with Ellis Grey, Meredith's mother, revealed, but similarly, the show addressed his battle with alcoholism, professional insecurities, and other personal problems.
Despite his repeated mistakes and disloyalty, Richard has grown as he eventually owns his mistakes. He accepted he had alcohol issues, sought treatment, and apologized to Meredith for his role in her discontented childhood. All his mistakes and what he learned from them played a big role in making Richard Grey's Anatomy's wise and determined leader.
9 Owen Hunt
Owen Hunt (Kevin McKidd) previously served in the Army before working in Seattle as the Head of Trauma Surgery. Although he is one of the more disliked characters on the show, the storyline about Owen's trauma from his experiences in Iraq is among Grey's Anatomy's most impactful.
The character's Post-Traumatic Stress Disorder (PTSD) symptoms were slowly revealed. Initially, Owen was always on guard for danger, although later, he was revealed to have flashbacks, nightmares, and panic attacks. As time passed, he learned how to better cope, eventually overcoming his struggles. Owen will return for Grey's Anatomy's twentieth season, meaning fans will revisit his character arc.
8 Jackson Avery
Jackson Avery (Jesse Williams) was introduced as one of the doctors from Mercy West after the merger in Season 6. Despite being the grandson of Harper Avery, he didn't boast his name, instead wanting to earn one for himself.
Jackson is rather impulsive and obnoxious in his earlier appearances. Similarly, he is quite stubborn regarding his beliefs, often dismissing others and their opinions. His differing beliefs from April are a huge reason their relationship doesn't work out. Jackson's character development is rather subtle as he evolves into a fine doctor who is neither arrogant nor condescending of other's beliefs.
7 Jo Wilson
Jo Wilson (Camilla Luddington) arrives in Season 9 as a surgical intern. Not only did she have a rough upbringing, but Paul Stadler, her first husband, was extremely abusive. Jo was able to leave and start a new life with a new name, making her progress from a victimized wife to an independent surgeon even more impressive.
Jo then enters a relationship with Alex Karev (Justin Chambers), becoming among the show's favorite couples. Alex's exit is one of Grey's Anatomy's game-changing moments, with many fans arguing it was inconsistent with his character arc. However, it demonstrated Jo's growth was independent of Alex's support, and she kept her strength even in the face of adversity.
6 Amelia Shepherd
Derek's youngest sister, Amelia Shepherd (Caterina Scorsone), relocates to Seattle and takes over as Head of Neurosurgery following his demise. Amelia's nickname, "Hurricane Amelia," is consistent with her personality as she is often very outspoken and chaotic.
Amelia is shown to be among the show's most flawed characters, making her character development more dynamic. Amelia's battle with the grief of losing her loved ones, the trauma she faced - including witnessing her father's brutal death at a young age - and her battle with addiction and relationship turmoil make her progress even more remarkable.
5 April Kepner
April Kepner (Sarah Drew) is perky and overly eager, making it difficult for her coworkers to take her seriously or view her as anything but annoying. Similarly, April is extremely insecure. However, as she makes a place for herself, she becomes increasingly confident in her skill as a surgeon.
She embraces her faith, and while she is initially shown as a pushover, April's persistent determination demonstrates that she is a compassionate doctor willing to fight for her patients. Additionally, her romance with Jackson is among the healthiest relationships in Grey's Anatomy, cementing April's status as a fine woman and an even better trauma surgeon.
4 Meredith Grey
Meredith Grey (Ellen Pompeo) was the show's titular character for nineteen years. As she begins her surgical internship, it is evident she is hard-working and intelligent despite often being overshadowed by her mother's legacy. Meredith endures considerable trauma throughout the seasons, especially during the earlier seasons.
Her strained relationship with her family and the associated abandonment issues made it difficult for her to maintain a romantic relationship with Derek Shepherd. One of Meredith's most interesting storylines was her therapy sessions with Dr. Wyatt. As the show's main character, Meredith experiences considerable growth, and fans loved watching every minute of it.
3 Alex Karev
Alex Karev was introduced in Season 1 as part of Grey's Anatomy's original interns. Despite being introduced as a pompous and rude character, Karev's character brought its share of magic to the show. Initially, Alex projected a callous, insensitive attitude towards patients, demonstrating his poor bedside manners. Similarly, he treated others with disrespect before befriending the other interns.
Throughout the seasons, Alex overcomes his arrogance and egoism. A patient once analyzed him, describing his behavior as a defense mechanism. Eventually, Karev becomes a good man and the kind of doctor who fights for his patient's recovery, even when they are unwilling to themselves. And while his exit nearly undid 15 years of character development, fans will always have what came before.
2 Cristina Yang
The hyper-competitive intern of the show's original five interns, Cristina Yang (Sandra Oh), is also one of Grey's Anatomy's best characters. Ambitious and driven, Cristina owned her talent. While her confidence was initially interpreted as arrogance, it was soon demonstrated to be a rabid passion for surgery.
Although her competitive drive never dwindled, Cristina's priorities evolved. Similarly, her compassionate nature extends to her patients, coworkers, and students. Initially dismissive of her fellow interns and unwilling to delegate, Cristina formed an unbreakable bond with Meredith and learned to take the time to teach her students.
1 Mark Sloan
Fans initially saw Mark Sloan (Eric Dane) as a narcissistic, insensitive and deplorable friend to Derek. In his first on-screen appearance, he describes himself as "self-destructive and self-loathing to an almost pathological degree." His storyline reveals his charming, rugged exterior masks his inner anguish about his estranged relationship with his parents and Derek.
While Mark tends to be callous about relationships, he eventually falls for Lexie Grey, becoming a committed guy. When Callie is pregnant with his baby, he steps up to become a father, something his past self would've never considered. Similarly, Mark was introduced as unwilling to teach or delegate, but he soon began taking an active teaching role, even mentoring Jackson.