Kelley Mack. Photo: Barry Brecheisen/Getty Images

Kelley Mack, the actress best known for portraying Adeline on season nine of The Walking Dead, “passed away peacefully” on August 4 in her hometown of Cincinnati, per a statement posted to the health-services social network CaringBridge. She had an astrocytoma, a cancerous tumor that grows in the central nervous system, that began in her spinal cord. She was diagnosed after spending Thanksgiving 2024 in the ER, began radiation in January 2025, and entered into respite care in July. Mack’s sister, Kathryn, confirmed her death on Instagram on August 5. “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,” she wrote. ‘I’m so fucking proud of her.”

In The Walking Dead, Mack’s Addy was a sweet girl living on the Hilltop with a crush on Matt Lintz’s Henry Sutton, who fought against that season’s antagonist, the Whisperers. The actress’s life will be honored with a celebration on August 16 in Ohio. “Kelley has already come to many of her loved ones in the form of various butterflies 🦋 ❤️,” her sister wrote. “She will be missed by so many to depths that words cannot express.”