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.  Following the announcement, some people online speculated that Mack died due to complications from the COVID-19 vaccine.

Kelley Mack, an actress best known for her role as Addy on the television series The Walking Dead, died last weekend, her family announced on Tuesday. She was 33. Mack was diagnosed with glioma, an aggressive tumor that affects the central nervous system, last year.

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.