Actress Kelley Mack (Kelley Lynne Klebenow), best known for playing Addy on season 9 of The Walking Dead, passed away on Saturday, August 2, 2025, in Cincinnati, Ohio, at age 33, after a hard-fought battle with diffuse midline glioma, an aggressive brain tumor located in the central nervous system.
The news was announced by her family on Instagram, mentioning that she died “peacefully” in the company of her mother Kristen and aunt Karen; the young actress had many plans in entertainment.
Kelley Mack’s diagnosis and medical course
The disease was detected in January 2025 after Kelley experienced symptoms such as persistent low back pain, neuropathic tingling and loss of mobility in the legs.
An MRI revealed the presence of this rare brain tumor that affects deep structures of the brain and spinal cord.
For weeks he shared his process on social media: he revealed that he had lost motor function in his right leg after a spinal cord biopsy, and was dependent on a walker and wheelchair.
Despite this, he completed proton radiation therapy in March 2025 and was able to regain some movement.
Artistic career and legacy
Although her role on The Walking Dead was brief – Addy appeared in five episodes between 2018 and 2019 during the conflict with the Whisperers – her performance resonated with the fan community for its emotional intensity and connection to the Hilltop shelter.
Kelley’s career included roles in series such as Chicago Med (as Penelope Jacobs) and an episode of 9-1-1.
He also participated in independent films such as Broadcast Signal Intrusion and Mr. Manhattan as well as outstanding short films such as A Knock at the Door, awarded at horror festivals.
She also worked as a producer, screenwriter and voice artist.
A graduate of Chapman University with a degree in cinematography, Mack combined her academic training with a passion for visual storytelling. Her last completed project was the film Universal, which is pending release.
Farewell message and reactions
Kelley’s sister shared on Instagram a touching message: “Such a bright and fervent light has transited to the afterlife…it has already reached many of her loved ones in the form of butterflies. We will miss her to a depth that words cannot express.”
Colleagues from The Walking Dead such as Alanna Masterson, Gustavo Gomez and director Michael E. Satrazemis expressed their grief at the loss of someone described as warm and radiant.
Te vamos a extrañar mucho Kelley, tus actuaciones y tu talento se quedan inmortalizados en tu trabajo
Actress’ case resonates in Latino community
For those living in the U.S., especially Hispanics interested in entertainment, health and awareness, the Kelley Mack case reinforces several themes:
The importance of awareness of rare tumors such as diffuse midline glioma, especially in young adults.
The value of publicly sharing the medical process as a form of inspiration and resilience.
How a young artist managed to make an impact with brief but significant appearances, demonstrating that passion and commitment can transcend the screen.
Kelley Mack passed away on August 2, 2025 at age 33 from an aggressive brain glioma.
Diagnosis, treatment and losses were openly shared with his community.
With a career that spanned television, film and behind-the-scenes roles, he left a creative and human legacy.
A ceremony to honor his life will be held on August 16 in Ohio, where family, friends and fans can pay tribute to his memory.
Find out more at ‘QueOnnda.com’.
