How Old Is Kat Graham? 1 of 2 Previous Autoplay Next Share Tweet November 30, 2012 at 03:00PM EST by Leslie Pandey Related: The Vampire Diaries, Kat Graham full size Credit: Jason Merritt/Getty Images Do You Know Kat Graham's Age? The talented Kat Graham plays high schooler-slash-witch Bonnie Bennett on The Vampire Diaries, but do you know how old Kat is in real life? Click through to find out if you’re right! Need your daily Vampire Diaries fix? Like us on our Facebook page, or follow us on Twitter!