Eight seasons is a lot of time for character development. The Vampire Diaries constantly put its entire set of main characters through the wringer. Many of the central characters die multiple times throughout the show's run. Every season, a new villain arrives in Mystic Falls to wreak havoc that could eventually lead to life-altering decisions or events. By the show's conclusion, everyone either became supernatural or was deeply involved in the world of vampires, witches, and werewolves. However, as events continued, they brought out the best and worst in everyone, depending on who was causing mayhem or why.
There were many significant characters in The Vampire Diaries, and each had a fleshed-out backstory and understanding of their motivations. But, not all of them were given the storyline they should have to make them more exciting. While some thrived, growing beyond what anyone initially thought would occur for them, others remained stagnant after a while, not necessarily growing or regressing. However, others got caught in repetitive storyline traps that prevented them from growing beyond it. As the series finally ended, everyone experienced some degree of things that transformed their worldview forever.
11 Alaric Saltzman
Although meant to be a vampire hunter, Alaric is mostly useless in the supernatural world. While his gadgets help him defend himself, and he helps teach Elena self-defense, Alaric is mainly used as a parental figure to Elena and Jeremy or a drinking buddy for Damon. His abilities as a vampire hunter do not come in handy when much quicker vampires surround him, and being dead for two seasons is not necessarily helpful to his character. Revived, Alaric spends more time as a researcher after he reverts to being human.
10 Matt Donovan
As the only central character to remain human from the pilot to the series finale and beyond, Matt Donovan should have been one of the biggest hearts of the show. As a reminder of the importance of humanity and what it stands for, Matt should have been far more important than he was. Instead, Matt usually ended up on the sidelines, especially as his character arc grew to despise vampires. Although his history with vampires justifies his anger toward them, none of this makes Matt the most compelling person.
9 Jeremy Gilbert
At first, Jeremy was just another human struggling to stay alive in a town filled with vampires. Although he died and returned to life several times throughout the series, Jeremy does not get a sense of urgency in the supernatural world for a while. However, his ability to communicate with Anna and Vicki while they are ghosts later comes in handy when Damon and Elena need to contact Rose. However, it is only after Jeremy becomes a member of the Brotherhood of the Five that things look up for him. As a Hunter, Jeremy is considered supernatural and is a vital member of the search for the cure to vampirism. When Jeremy finally leaves Mystic Falls, he does so with the intent of continuing his search for vampires.
8 Tyler Lockwood
Tyler is a popular jock and a jerk at first. But, empathy is forced on him when Tyler discovers the Lockwood family holds the werewolf gene, and he must be careful of the risk of triggering his own. Tyler is terrified of the transition when it does happen, and his desperation to understand what being a werewolf means for him results in a selection of controversial choices. Becoming a Hybrid eventually becomes involved in Tyler's continued strive to break the sire bond he has toward Klaus and his eventual desire for revenge after Klaus kills Tyler's mother.
7 Enzo St. John
Enzo started on the verge of villain and anti-hero, having come from being tortured for decades and being left behind by Damon. However, when Enzo returns to life, he wants a family or a connection after spending so much time alone and initially searches for that in Lily Salvatore. After that fails, Enzo finds brotherhood in Damon and an unexpected but light-in-the-dark romance with Bonnie. Enzo developed immensely since his initial introduction, being willing to give up being a vampire for a human life with Bonnie. Sadly, things do not work out for them, but that does not diminish Enzo's growth as a character.
6 Damon Salvatore
Although Damon has loads of charisma, making him one of the most entertaining characters to watch, he is also one of the most problematic. Damon spends season one as a villain, compelling Caroline to do as he says and stripping her free will away. He even starts season two by snapping Jeremy's neck. Damon's character growth, as it occurs, is explained through his connection to Elena rather than wishing to grow for himself. Damon admits his selfish behavior, something he is never quite able to grow out of. However, in the series finale, Damon is finally willing to sacrifice himself, showing a piece of him that Damon had not shown since he was human.
5 Stefan Salvatore
For all of Stefan's good qualities, he also had many difficult ones. Stefan constantly showed regret and remorse for his actions as a Ripper and seemed to feel the most guilt for how his actions affected others. Stefan is always willing to sacrifice himself for others, a trait that emerges again in the series finale. His patience also helps Caroline by teaching her how to adjust to being a vampire. But Stefan also falls into several repetitive storylines. Removing Stefan's humanity was exciting initially but happened too often after season three to make him a villain again. Stefan's selflessness, a trait that engineers his self-sacrificial tendencies, can be considered noble. But, it also seems frustrating when Stefan is always willing to die for Damon, but it never comes across that Damon is ready to go nearly as far for Stefan.
4 Elena Gilbert
Elena suffers from constant repetition as well, to a degree. The love triangle, or a tug-of-war for Elena between Stefan and Damon, is a continuous element of the show. Due to her being a Doppelgänger, Elena is also at the center of nearly everything, as her blood is a crucial element in many supernatural loopholes. Although Elena's biggest wish had been to protect her loved ones from harm, they all usually risked their lives for her anyway. But that does not diminish Elena's willingness to step up to protect her friends and family to the best of her ability.
3 Katherine Pierce
While Elena may be the nicer Doppelgänger, Katherine was arguably far more interesting. Having been alive for over 500 years, she has centuries of backstory and motivation for her actions. Katherine is a survivor to the highest degree and proves that while a redemption arc can be nice, it is unnecessary to make an antagonist exciting. Katherine is a villain to the bitter end, having gone above and beyond in her search for what she considers to be her own happiness. Although Katherine may not be a hero, Katherine is direct, even when she is manipulating others, as everyone tends to know exactly where they stand with her or how she thinks of them.
2 Bonnie Bennett
Bonnie is someone who very much deserved better than what The Vampire Diaries offered her. At any given moment, Bonnie was more often used as a plot device than a character in her own right. Always needed to use magic to get her friends out of a jam, Bonnie went above and beyond to save her loved ones, even at the sacrifice of her own life. Bonnie was tortured or in pain repeatedly but always found a way to win in the end. Bonnie proved herself repeatedly as a capable witch and earned far more happiness than she ever received. As the savior of Mystic Falls, Bonnie's conclusion of seeing her leave town to travel the world while fully embracing and understanding what she is capable of worked as a conclusion for Bonnie.
1 Caroline Forbes
Caroline kept her bubbly charisma even after becoming a vampire. However, that did not stop her from being taken seriously. Caroline positively impacted those around her, tending to see the best in others. However, becoming a vampire also kept her character development to the point where Caroline reveals she has been better off as a vampire than while being a human. Caroline embraces being a vampire better than anyone else, keeping all of her best qualities as she continues to grow into advanced versions of herself. Caroline's growth is also noticeable in her appearances throughout The Originals and Legacies.