Kelley Mack, known for her portrayal of Addy in Season 9 of The Walking Dead, passed away at 33 on August 2, 2025, in Cincinnati, Ohio, following a brave battle against diffuse midline glioma—a rare and aggressive brain tumor that affects the central nervous system.
Kelley Lynne Klebenow, born on July 10, 1992, was cherished by her family and friends as a beacon of creativity, kindness, and steadfast bravery.
Mack initially observed symptoms in late 2024: ongoing lower back discomfort and neuropathic feelings in her right leg, prompting a spinal MRI that uncovered a tumor in her spinal cord.
After being diagnosed with diffuse midline glioma in January 2025, she had spinal surgery and received proton radiation treatment. The procedure resulted in the inability to use her right leg and considerable impairment in her left, making her dependent on a walker and wheelchair.
In spite of her health difficulties, Mack stayed openly honest and resolute. In March 2025, she posted a video of herself practicing walking again, joyfully marking the minor achievement with her usual wit: “Life has had its highs and lows recently, wouldn’t you say?” Her times of strength and genuineness impacted countless fans and colleagues.
A Hinsdale Central High School graduate (class of 2010) and an alum of Chapman University’s Dodge College of Film and Media Arts (2014), Mack built a diverse portfolio: 35 acting credits and
five producing credits. Her roles went beyond The Walking Dead to feature in Chicago Med (as Penelope Jacobs), 9‑1‑1, and several independent films including Broadcast Signal Intrusion and Delicate Arch.
Moreover, she provided her voice for advertisements featuring brands such as Dr. Pepper, Dairy Queen, Ross Stores, and Chick-fil-A, and also acted as a voice match for Hailee Steinfeld’s Gwen Stacy in promotional content for Spider-Man: Into the Spider-Verse.
Mack’s last on-screen role will be in the upcoming film Universal, in which she played Ricky. She was also credited as an executive producer on the project.
Relatives and supporters both grieved her loss. On Instagram, her sister Kathryn referred to Kelley as “a vibrant, passionate light” whose bravery and spirit motivated numerous people. Her mother Kristen, father Lindsay, sister Kathryn, brother Parker (who is also an actor), grandparents Lois and Larry, and boyfriend Logan were reported to be with her as she peacefully passed away at home.
A service to celebrate her life is scheduled for August 16 in Glendale, Ohio, with further arrangements to commemorate her memory in Los Angeles at a future time.
In commemorating Kelley Mack, colleagues, friends, and admirers penned tributes that emphasized not only her skill but also her compassion, creativity, and encouraging spirit. In The Walking Dead, actress Alanna Masterson expressed her pride in having battled alongside her during their concluding episode together. Numerous individuals noted that Mack’s authentic enthusiasm and cooperative nature left a memorable impression on the sets she adorned and the audiences she engaged.
Although her life ended prematurely, Kelley Mack leaves a legacy of narrative, poise in the face of challenges, and a steadfast passion for her craft. Her contributions—ranging from genre television to voiceover and production—reflect her commitment and enthusiasm
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