Speaking to the New York Post, Graham refused to reveal too many details about what will happen as the season comes to a close.
However, she said: "They're the craziest episodes... There's so many changes in the show - so many people are dying!
"This crazy Klaus character has come into the picture and is putting everyone at risk... and takes out a few people."
Graham added that her character Bonnie has "a lot of responsibility on her shoulders" because Jonas (Randy J Goodwin) gave her the power to kill Klaus (Joseph Morgan).
"Bonnie always bites off more than she can chew," she said. "That's nothing new. But I'm glad that fans are in a tizzy [about what's coming up] because they absolutely should be - they should be scared to death."
The Vampire Diaries returns tonight at 8/7c on The CW in the US and on Tuesday at 9pm on ITV2 in the UK.
> 'Vampire Diaries' star: 'Someone will die'
Watch the extended trailer for the next episode of The Vampire Diaries below: