Kelley Mack, a rising star in the entertainment industry, passed away at the age of 33 in August 2025 after a courageous fight against a rare form of brain cancer known as diffuse midline glioma. Mack, who gained recognition for her role as Addy in season 9 of The Walking Dead, was celebrated not only for her acting skills but also for her work as a producer and voiceover artist. Her career had recently gained momentum, and she actively promoted upcoming projects even during her illness.
Kelley Mack’s Journey with Cancer
Mack’s health challenges began in January 2025 when she announced her diagnosis of diffuse midline glioma, a type of astrocytoma. In her own words, she described the onset of symptoms that started with persistent lower back pain and progressed to severe neuropathic issues in her legs. She shared her experience on social media, stating, “For a month after that, I had persistent lower back pain and thought I slipped a disc.”
The actress underwent emergency MRIs on Thanksgiving Eve, which revealed an abnormal mass in her spinal cord. Following a biopsy, she unfortunately lost mobility in her right leg and much of her left leg, requiring the use of a walker and wheelchair. Despite the immense challenges, Mack maintained a positive outlook. She communicated to her followers that her acting career would be “somewhat paused for a little” during her treatment but remained optimistic about future projects.
Understanding Diffuse Midline Glioma
A glioma is a malignant tumor that arises from glial cells, which support the central nervous system. According to the Cleveland Clinic, gliomas can be classified into three main types: astrocytomas, ependymomas, and oligodendrogliomas. Mack’s diagnosis of diffuse midline glioma falls under the astrocytoma category, which can manifest in various forms, including glioblastomas and diffuse intrinsic pontine gliomas (DIPGs).
The National Cancer Institute elucidates that diffuse midline gliomas can occur in both the brain and spinal cord, making them particularly challenging to treat. Mack’s case highlights the aggressive nature of this type of cancer and the limited options available for patients facing such diagnoses.
Kelley Mack’s dedication to her craft and her resilience throughout her illness inspired many. While the exact cause of her death has not been disclosed, her legacy will continue through the characters she portrayed and the impact she made in the entertainment industry.
