Kelley Mack, an actor who starred in "The Walking Dead," died due to complications from the COVID-19 vaccine. Actor Kelley Mack, who was best known for playing Addy on the TV show "The Walking Dead," died at age 33 on Aug. 2, 2025, her sister announced in an Instagram post.

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 her Instagram page Tuesday.

Actress Kelley Mack was starting to become a regular presence on our TV screens before her death at age 33. Mack got her start in short films and small TV roles before joining bigger productions like The Walking Dead, 9-1-1 and Chicago Med. She was outspoken about how playing Addy on the post-apocalyptic show introduced her to an online fanbase.