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.

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.

Kelley Mack, who portrayed Addy in Season 9 of The Walking Dead, has died at the age of 33. Her family announced that Mack passed away on Aug. 2 in her hometown of Cincinnati following a diagnosis of glioma of the central nervous system.