Kelley Mack, an actress known for her portrayal of Addy in The Walking Dead, died on August 2, 2025, her family announced. She was just 33. Since Mack died at such a young age, fans are mourning her death while wondering what the cause of death was. After all, the late voiceover artist was promoting upcoming film roles during the final months of her life, so her death shocked her fans and industry peers.
Mack’s sister penned a heartfelt farewell statement to the actress’ Instagram page on August 5. The announcement noted that Mack died “peacefully” with her mother and aunt by her side.
“It is with indelible sadness that we are announcing the passing of our dear Kelley,” the statement began. “Kelley has already come to many of her loved ones in the form of various butterflies. She will be missed by so many to depths that words cannot express.”
Mack’s sister elaborated that she “would want you all to know how much she loves you. And as her sister, I want you all to know how brave that tough SOB was, especially when she decided to make the leap to be reunited with God. I’m so f**king proud of her.”
Below, Hollywood Life is remembering Mack for her life and career in addition to her health battle before she died.
Who Was Kelley Mack?
Mack was an actress, voiceover artist and producer. According to her IMDb profile, the Ohio native also dipped into other production work. As an actress, she was recognized for her performances as Addy in The Walking Dead, Alice in Broadcast Signal Intrusion and Penelope Jacobs in Chicago Med.
On top of acting, Mack knew she loved other parts of storytelling. She studied film production and cinematography, per her IMDb page, and she produced a film that landed on AMC’s Shudder and won the Jury Choice Award at the Atlanta Horror Film Festival.
Kelley Mack’s Cause of Death: How Did She Die?
Mack was battling a rare form of astrocytoma cancer called diffuse midline glioma, she revealed in January 2025. Astrocytoma is a type of brain tumor, and diffuse midline glioma is a tumor that begins in the brain or spinal cord, according to the National Cancer Institute.
Although Mack’s family did not disclose her official cause of death, she died after her strenuous cancer battle. Mack’s IMDb profile also indicates that she died following the cancer of the central nervous system.
Kelley Mack’s Health & Cancer Battle
In January 2025, Mack opened up about her diagnosis with diffuse midline glioma in an Instagram post. She shared photos of her hospitalization.
“In September, I moved into a new apartment with my boyfriend, Logan. For a month after that, I had persistent lower back pain and thought I slipped a disc,” Mack wrote in her caption. “A few weeks later, I had neuropathic itching in my right quad. And then, the shooting pains in my legs and back began, which resulted in me having to sleep in a recliner for a month because laying down was too painful. On Thanksgiving Eve, I had emergency MRIs done at the hospital, which revealed an abnormal mass in my spinal cord.”
Mack pointed out that, “due to the biopsy surgery on [her] spinal cord, [she had] lost the use of [her] right leg and most of [her] left leg,” which affected her ability to walk. Mack had to use a walker and wheelchair as a result.
At the time, the actress pointed out that she would undergo radiation treatment in Cincinnati, Ohio. In March, Mack noted in a separate Instagram post that her health was improving. During her final months, Mack continued to promote her on-screen work.
