Kelley Mack’s death on Aug. 2 at age 33 was "very unexpected," her rep tells PEOPLE. The 'Walking Dead' actress was still auditioning in June despite her cancer diagnosis and her agents were "totally surprised" by the news.

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.

Kelley Mack, best known for her role as Addy in "The Walking Dead," has died at the age of 33 after a difficult fight with brain cancer. Her sister, Kathryn Klebenow, announced the sad news on Tuesday through Mack's Instagram. "It is with indelible sadness that we are announcing the passing of our dear Kelley," she wrote.