Actress Kelley Mack, best known for her roles in The Walking Dead and 9-1-1, has passed away at just 33 years old after a heartbreaking battle with cancer. Her family confirmed that she died peacefully on August 2 in her hometown of Cincinnati, Ohio.
Born Kelley Lynne Klebenow, Mack had been fighting glioma of the central nervous system—an aggressive and rare form of cancer. Her sister, Kathryn Klebenow, shared the emotional news in a post on Mack’s Instagram, writing, “Such a bright, fervent light has transitioned to the beyond, where we all eventually must go.”
According to her sister, Kelley was surrounded by love in her final moments, with her mother Kristen and aunt Karen by her side. “Kelley has already come to many of her loved ones in the form of various butterflies,” the post added. “She will be missed by so many to depths that words cannot express.”
Mack first went public with her diagnosis back in January. In a deeply personal Instagram post, she detailed her symptoms—starting with back pain she initially thought was a slipped disc, followed by nerve pain and eventually loss of mobility in her legs. An emergency MRI on Thanksgiving Eve revealed a mass in her spinal cord.
“I have been diagnosed with diffuse midline glioma,” she wrote, adding that the biopsy left her unable to walk unassisted. “So I now get around with a walker and a wheelchair.” Her final health update came in March, when she shared a video of herself re-learning to walk.
Born on July 10, 1992, Mack’s journey in storytelling began early. A mini video camera gifted for her birthday sparked her love of filmmaking—a passion she would carry through childhood and into a career both in front of and behind the camera.
Though she gained widespread recognition as Addy in Season 9 of The Walking Dead, Mack built a diverse resume across television and film, including roles in Chicago Med and 9-1-1. She also worked as a producer, earning acclaim for the award-winning horror film On The Black, which she co-wrote with her mother and was later distributed by AMC’s Shudder.
Mack’s talents weren’t limited to the screen. She was a gifted voice actor, appearing in major projects like the Oscar-winning Spider-Man: Into the Spider-Verse. She also starred in multiple national ad campaigns, including a Rakuten commercial filmed earlier this year alongside her mom.
Beyond her professional achievements, Mack was known for her vibrant spirit and love for life. An adventurous soul, she found joy in hiking, biking, playing tennis and piano, and spending time with loved ones. “She cherished time with her family and friends, finding joy in collaboration and storytelling,” her family shared. “Her infectious enthusiasm and dedication to her work inspired countless others in the industry and beyond.”
Mack is survived by her parents, Kristen and Lindsay Klebenow; her sister, Kathryn; her brother, actor Parker Mack; her grandparents, Lois and Larry Klebenow; and her boyfriend, Logan Lanier.