I know I'm a bit late for this subject matter as we look toward The Vampire Diaries Season 7 on Oct. 8th but I've actually had this article saved on my drive for a while. I'm just going to jump right to it and SPOILERS obviously.
Mason was the younger brother to Richard Lockwood and uncle to Tyler Lockwood. He was a werewolf and honestly a pretty stand up guy. He came into the VD universe in Season 2 searching for the moon stone to give to Katherine.
His werewolf curse was activated with an accidental death that was completely Katherine’s doing and she is really to blame for any negative aspect of his character.
Mason was killed by Damon Salvatore for reasons that were really weak, even by Damon standards. It would have been really great to see Mason stick around longer to help Tyler with his own werewolf curse and maybe level out his hot-headed nephew. There aren’t many positive werewolf characters and Mason would have easily filled that void. The only reason I could see for his death was to further the Caroline/Tyler relationship (which I felt was a forced relationship anyways and did nothing for either of their characters' growth).
Sheila was the mother to Abby Bennett and grandmother to Bonnie Bennett (now that I'm thinking about it, why doesn't Bonnie have her dad's last name? Did he take her mom's maiden name as his own?). She was a powerful witch with a lot of wisdom and fierceness when it came to protecting her family.
Sheila appeared in Season 1 for only 4 episodes before perishing in episode 14 due to over-usage of her magic. With the loss of her mentor, Bonnie goes off the rails and her character really becomes irritating. Sheila easily should have lasted the entire first season and even the second which would have rounded Bonnie’s character more. It also would have made her death mean so much more. Her death, like the others on this list, was very rushed and purposeless in the current story.
Looking back to how season 6 ended, while I'm glad Elena will probably never return to the show, it's a pretty tough choice to which character I find more annoying: Elena or Bonnie.
Jenna was the younger sister to Miranda Gilbert and aunt to both Elena (adoptive aunt anyway) and Jeremy Gilbert. As one of the few still human characters in the main cast, her character was refreshing. The writing for her character was that of a Felicity Smoak from Arrow; goofy, awkward, but still strong.
Her death in Season 2 was random if anything. Why Klaus would pick to turn a human, that he had to use Katherine to lure out of the safety of her home, rather than just grab any of the dozens of vampires running around Mystic Falls...is beyond me. Sure, you could argue he wanted to punish Elena for making his life a living hell but even that doesn’t make much sense since he was going to kill Elena minutes later.
Klaus normally likes to torture with lasting effects for payback. I’m honestly convinced the VD writers want all their characters to be orphans with the loss of the Lockwoods, Gilberts, Forbes', and Bennetts. With Jenna’s death we also lost Jenna/Alaric which was sweet and goofy and I loved every second of it.
Lexi was the vampire mentor and best friend to Stefan Salvatore. She died in literally the same episode she appeared in Season 1, which by most show standards is pretty crazy.
She was killed by Damon Salvatore in a lamebrain scheme to convince the counsel that he was one of them. Her death was mostly unneeded since Damon already had most of the counsel wrapped around his finger by this time.
Lexi was badass and a much better role model for young female viewers, unlike Elena who is mostly concerned with which Salvatore brother she wants to kiss up to that week. Along with Mason, her character seemed to be purely good which I feel like VD lacks in its cast (with the exception of Caroline and maybe Matt). She did get a couple chances to return as a ghost but I felt like she had so much more to offer the show.
Slater was a minor character who appeared in Season 2. He had spent his vampire life earning multiple college degrees in pretty much anything you could think of. He’s highly knowledgeable and could have been a great asset to the VD cast as their go-to supernatural bookworm.
Alaric tends to have this role but often times he comes up short. I can’t help but think an immortal vampire has the jump on him as far as having the time to learn anything and everything on the supernatural world. He was compelled into killing himself by Elijah; which after getting to know Elijah’s character on The Originals it seems a bit out of character for him to just kill someone who hadn’t harmed or threatened his family. Slater’s death was actually depressing for such a short-lived character.
Last but certainly not least:
Sheriff Elizabeth Forbes
Elizabeth Forbes was the mother of Caroline Forbes and the sheriff in Mystic Falls. She held on longer than any character on this list by far which means her death, to me, was the hardest to watch.
Caroline is possibly my favorite character in the VD universe so watching her lose both her parents in tragic ways was heartbreaking. Elizabeth's death cemented in my mind that the writers of VD want all their main characters to be orphans with no living family. On a side note the fact that vampire blood can't cure cancer seems like a stretch. It can heal basically any wound or trauma and pull people back from death but it can't heal cancer cells? Come on.
The Vampire Diaries' writers are getting lazy and sadly I don't think the show is going to make it much longer. I hope that with the loss of two of the most annoying characters, Elena and Jeremy, the show can stay afloat on the backs of Damon and Stefan.