The entertainment world was heartbroken this week as news spread of Kelley Mack’s passing at just 33 years old. The actress, best known for her roles in The Walking Dead and Chicago Med, died on August 2 in her hometown of Cincinnati after a courageous fight against a rare and aggressive form of cancer called diffuse midline glioma (DMG). Her family confirmed her death in a touching Instagram post, describing her as a “bright, fervent light” who faced her illness with unwavering bravery.
Mack’s diagnosis came in January 2025, when she revealed that a biopsy on her spinal cord had left her with limited mobility, requiring a walker and wheelchair. Despite the challenges, she remained hopeful, sharing updates on her progress, including a video of herself walking upstairs just months before her passing. Her openness about her struggle brought attention to a devastating disease that few understand, until now.
What Is Glioma of the Central Nervous System?
Glioma is an umbrella term for tumors that arise from glial cells, the supportive tissue of the brain and spinal cord. These cells normally help neurons function, but when they mutate and grow uncontrollably, they form tumors that can be either slow-growing or highly aggressive. Mack’s specific type, diffuse midline glioma (DMG), is one of the most lethal forms. It typically develops in critical areas like the brainstem, thalamus, or spinal cord—regions that control vital functions like breathing, movement, and consciousness.
What makes DMG so deadly is its diffuse nature, meaning it spreads widely through healthy tissue, making surgical removal nearly impossible. It’s also highly resistant to chemotherapy and radiation, leaving patients with very few treatment options. While DMG is most commonly diagnosed in children between 5 and 10 years old, Mack’s case highlights that it can strike adults as well.
Symptoms of glioma vary depending on the tumor’s location but often include persistent headaches, seizures, vision problems, slurred speech, and loss of motor function. In Mack’s case, the tumor affected her spinal cord, leading to partial paralysis in her legs. Doctors still don’t fully understand what causes gliomas, though genetic mutations, radiation exposure, and family history may play a role.
You Might Like: Buccal Fat Removal: Jenna Ortega’s Plastic Surgery
A Legacy of Strength and Art
Beyond her health battle, Kelley Mack was a talented actress and filmmaker with a passion for storytelling. She got her start in commercials as a child and later earned acclaim for her role as Addy in The Walking Dead and Penelope Jacobs in Chicago Med. She also voiced Gwen Stacy in Spider-Man: Into the Spider-Verse and worked on independent films like Broadcast Signal Intrusion and Mr. Manhattan.
Mack’s creativity extended behind the camera as well. She wrote, directed, and produced short films and was working on a feature-length project, Universal, at the time of her death. Her family has announced a remembrance service in Ohio on August 16, with a celebration of life in Los Angeles to follow.
Kelley Mack, known for her role in season 9 of The Walking Dead, passed away at the age of 33 after battling central nervous system glioma pic.twitter.com/KDoqPz8Rn7
— Pubity (@pubity) August 6, 2025
Her sister’s heartfelt tribute captured the essence of Mack’s spirit: “She would want you all to know how much she loves you… 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—ing proud of her.”
While research into DMG and other gliomas continues, Mack’s story underlines the urgent need for better treatments and the importance of cherishing every moment. Her light may have dimmed too soon, but her courage and artistry will live on.
