In last night's Halloween-themed episode, Vicki, who recently became a vampire, was staked - and the show's executive producer says the character will not be returning.
"No-one's safe on this show," Williamson told TV Guide. "We've reached the point when we're watching TV that there's no jeopardy, no risk, no stakes, when we know our lead characters aren't going to be killed.
"Well, that's not true on this show. I'm starting with the supporting characters and I'm working my way in. Everyone's going to die on this show. This is a show where characters you love may die, and it'll be unexpected and shocking, so get ready for it. It's as simple as that. And [Vicki] was the first casualty."
He also explained that he felt the time was right for Vicki to leave because he didn't want her relationship with Jeremy to mirror that of Bill and Sookie on HBO's True Blood.
"Where would that story go? A love story between a vampire and a guy? We're watching that on True Blood. And it's beautiful on True Blood.
"It doesn't mean we can't tell that same story in a different way, but we have other plans for Jeremy. I like Jeremy, I like bringing another guy to the show. I take him down another road."
Williamson revealed that Jeremy has a big storyline coming up which kicks in when a new teacher - Alaric - shows up.
The Vampire Diaries continues Thursdays at 8pm on The CW.