Kelley Mack, who played Hilltop resident Addy on 'The Walking Dead' and appeared in Dr Pepper's 'Fansville' ads, dies of a rare form of cancer at age 33.

Actor Kelley Mack, best known for playing Addy on "The Walking Dead," died over the weekend, her family announced. She was 33. "Such a bright, fervent light has transitioned to the beyond, where we all eventually must go," her sister Kathryn wrote on Mack’s Instagram on Tuesday.

At the time of her death, the Ohio-born actor had been actively promoting the independent sci-fi feature "Universal," in which she has a starring role.