Alexia “Lexi” Branson is a beloved yet short-lived character from The Vampire Diaries. In season 1, episode 8, she is killed by Damon Salvatore after living for 350 years. Lexi is introduced as Stefan Salvatore's close friend and confidante in The Vampire Diaries. She helps Stefan control his violent tendencies and reminds him of his human side. Lexi is portrayed as a charming and joyful vampire who once fell in love with a man and turned him into a vampire.
In episode 8, titled 163 Candles, Damon Salvatore meets Lexi and others at the grill while already framing Lexi for several vampire attacks in the background. He informs the Sheriff of her location, and when Lexi turns to the Sheriff in her defense, Damon conveniently arrives and suddenly stabs her heart.
Who killed Lexi in The Vampire Diaries?

Her sudden death shocked the fans, but her connection with Stefan and her charming personality made her a beloved character. She still appears in flashbacks in later episodes of the series.
The episode opens with Lexi arriving in Mystic Falls to surprise Stefan on his birthday. The two share warm, affectionate moments. Lexi is portrayed as bubbly, lively, and quickly becomes a grounding presence for Stefan. That night, they go out to celebrate at the Mystic Grill.
At the grill, she meets Elena and Caroline. Lexi proves helpful even for Elena when she offers heartfelt advice about love and Stefan's struggles as a vampire. The meet-up is then joined by Damon, who acts friendly. Stefan becomes wary, Lexi plays along, unaware of Damon's plans.
Behind the scenes, Damon is already aiding the Mystic Falls Council by "helping" them identify the person behind several vampire attacks. He tries to deflect suspicion from himself and chooses Lexi as the scapegoat. At the grill, Damon slips a vervain injection into her drink, weakening her so she can’t fight back effectively. He then informs the Sheriff of her location, and they arrive there.
As Sheriff drags Lexi outside after injecting her with another drug, Damon approaches her pretending to be unaware and siding with Lexi. But when Lexi activates her empire mode in defense and the Sheriff's gun fails to work on her, Damon intervenes and stabs her in the heart with a wooden stake, killing her.
In her last moments, Lexi asks her the reason for his betrayal, to which Damon simply answers,
"it was part of the Plan"
What does Lexi's death mean in The Vampire Diaries?
Lexi's death is extremely significant in The Vampire Diaries because it emphasizes that no character is ever truly safe, regardless of how powerful or charming they may be. Vampires have supernatural abilities and longer lifespans than humans, but Lexi's death reminds us that they are not invincible and can be killed instantly.
After her death, Stefan finds her body while Damon claims he killed her for good to protect themselves from being discovered. Therefore, in season 1, Damon is portrayed as the antagonist driven by selfish motives. Killing Lexi was a strategic move to avoid suspicion from the council and to eliminate a serious threat.