Actress Kelley Mack, known for her appearance in post-apocalyptic zombie drama “The Walking Dead,” has died. She was 33.

Kelley Mack, famous for her roles on "The Walking Dead" and "Chicago Med" has died of cancer at age 33. Her sister, Kathryn, announced Mack's passing Tuesday on Mack's Instagram page. Mack died Saturday according to the post.

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.