'Walking Dead' Actress Kelley Mack Has Died at Just 33 Years Old — What Was Her Cause of Death?
Mack was best known for her performance as Addy in 'The Walking Dead.'
Published Aug. 6 2025, 11:08 a.m. ET
Actress Kelley Mack, who was best known for her work on The Walking Dead, has died at just 33 years old. Kelley, who had also made appearances on 9-1-1 and Chicago Med, was in her Cincinatti home at the time of her death, according to the social media site CaringBridge.
Given that she was just 33, many wanted to better understand what Kelley's cause of death was. Here's what we know about what happened to her.
What was Kelley Mack's cause of death?
According to the obituary published on CaringBridge, Kelley died as a result of a glioma in her central nervous system. A glioma is a type of tumor that can affect the brain or the spinal cord.
"It is with indelible sadness that we are announcing the passing of our dear Kelley. Such a bright, fervent light has transitioned to the beyond, where we all eventually must go," a post on her Instagram read.
"Kelley passed peacefully on Saturday evening with her loving mother Kristen and steadfast aunt Karen present. Kelley has already come to many of her loved ones in the form of various butterflies," the post continued. "She will be missed by so many to depths that words cannot express." A celebration of life is apparently planned for Aug. 16 in Ohio.
Kelley was best known for 'The Walking Dead.'
Kelley is likely best known for her role as Addy on The Walking Dead, where she played a resident of the Hilltop Community and appeared in the show's ninth season. She also appeared on shows like 9-1-1 and Chicago Med, as well as in smaller parts in a number of other series.
As the post about her death on Instagram explains, she reached a huge number of people through her work as a performer.
Kelley was receiving end-of-life care in the days before her death.
As posts on Caring Bridge from Kelley's family make clear, she was receiving end-of-life care in the days leading up to her death, and was spending that time dreaming of family and friends.
"Our beloved Kelley is receiving respite care at this time. She is experiencing the toughest part of her journey and could use emotional support and smiles," the post reads. "The family is asking for privacy during this sensitive time, but welcome any messages you'd like to send to Kelley."
Kelley's extended obituary dives into her credits, which also include voice work for Spider-Man: Into the Spiderverse and appearances in a number of other films and TV shows. Unfortunately, her illness cut short her time working in front of the camera, but it's clear that Kelley's life touched a great number of people, including some that she never knew personally.
Kelley's CaringBridge page is still accepting donations, and also includes information about her celebration of life. The family have also said that they are planning a celebration of life in Los Angeles at some point in the future.