The entertainment world is mourning the untimely passing of Kelley Mack, an actress widely recognized for her role as Addy in the acclaimed television series The Walking Dead. Kelley passed away on August 2, 2025, at the young age of 33, after a courageous battle with diffuse midline glioma, a rare and aggressive form of central nervous system cancer.
Though her career in film and television was still blossoming, Kelley Mack left an indelible impact on fans, colleagues, and the broader entertainment community. This article honors her life, career achievements, personal journey, and the legacy she leaves behind.
Early Life and Education
Kelley Mack was born as Kelley Lynne Klebenow on July 10, 1992, in Cincinnati, Ohio. From an early age, she showed interest in storytelling and performance. Her creativity was evident in childhood through her passion for acting, writing, and visual arts.
She graduated from Hinsdale Central High School in Illinois and went on to attend Chapman University’s Dodge College of Film and Media Arts, where she earned a Bachelor of Fine Arts in Cinematography in 2014. Her background in both performance and behind-the-scenes work gave her a well-rounded understanding of the film industry.
Kelley Mack’s Acting Career
Early Career and Breakthrough
Kelley began her professional journey in short films and commercials. One of her first noted performances was in The Elephant Garden, which gained attention at independent film festivals and marked her as a promising talent.
However, it was her portrayal of Addy in Season 9 of The Walking Dead that brought her widespread recognition. Though appearing in only five episodes, her character was part of a key storyline and became a fan favorite for her resilience and heart.
Television Roles
In addition to The Walking Dead, Kelley made appearances in several other popular TV shows:
- Chicago Med – portrayed Penelope Jacobs in a guest episode
- 9-1-1 – took on a minor but impactful role in the emergency services drama
These roles demonstrated her ability to perform across various genres, from horror and suspense to medical and procedural dramas.
Film Work
Kelley Mack’s film career included roles in both indie and mainstream productions. Some of her notable movie credits include:
- Broadcast Signal Intrusion (2021) – a psychological horror-thriller where she played a lead role
- Delicate Arch (2024) – a drama set in Utah’s national parks, exploring themes of solitude and healing
- Universal (2025) – her final film project, which she also executive produced
The release of Universal shortly before her death stands as a testament to her dedication and creative passion, even while battling illness.
Voice Acting and Production
Kelley was also active as a voice actor, notably doing voice matching for Gwen Stacy from Spider-Man: Into the Spider-Verse for merchandising and promotional content.
In addition to acting, she explored screenwriting, producing, and even some directing, further expanding her footprint in the entertainment industry.
Personal Life and Interests
Kelley was known by her family and friends as a deeply empathetic and energetic person. She enjoyed a wide range of activities, including:
- Hiking
- Tennis and pickleball
- Playing the piano
- Photography and visual arts
She was also a vocal advocate for mental health awareness, environmental causes, and women in film. Those who knew her described her as someone who lit up every room and always extended kindness to others.
Illness and Battle with Glioma
Initial Symptoms
In mid-2024, Kelley began experiencing persistent lower back pain. Initially dismissed as a muscular issue or slipped disc, the discomfort worsened over the following months. Soon, she experienced nerve irritation, including itching and weakness in her lower limbs.
An MRI conducted in early 2025 revealed a spinal tumor. Further tests confirmed the diagnosis: diffuse midline glioma, a rare and fast-growing type of brain or spinal cord cancer.
Treatment and Decline
Kelley underwent surgery and other treatments but lost the ability to walk after her operation. Despite this, she remained resilient and open about her condition, often sharing her experiences with fans and followers on social media.
She pursued physical therapy with determination, and her family supported her recovery efforts every step of the way. Unfortunately, due to the aggressive nature of the disease, her health deteriorated rapidly in mid-2025.
Her Final Days
On August 2, 2025, Kelley passed away peacefully at her home in Cincinnati, surrounded by her mother, aunt, and loved ones. Her sister, Kathryn Klebenow, shared the heartbreaking news on social media, writing that Kelley was a “bright, fervent light” and that she “transitioned peacefully into the beyond.”
A celebration of life is scheduled to take place on August 16, 2025, in Glendale, Ohio, where family, friends, and fans are expected to gather to honor her memory.
Kelley Mack: Life & Career Summary Table
| Attribute | Details |
|---|---|
| Full Name | Kelley Lynne Klebenow (Stage Name: Kelley Mack) |
| Date of Birth | July 10, 1992 |
| Date of Death | August 2, 2025 |
| Age at Death | 33 years |
| Place of Birth | Cincinnati, Ohio |
| Notable Role | Addy in The Walking Dead Season 9 |
| Education | BFA in Cinematography, Chapman University |
| Cause of Death | Diffuse Midline Glioma (a rare spinal/brain tumor) |
| Family | Mother (Kristen), Sister (Kathryn), Brother (Parker) |
| Notable Works | Broadcast Signal Intrusion, Chicago Med, Universal |
| Other Talents | Voice acting, producing, screenwriting |
Tributes from Fans and Colleagues
Since her passing, tributes have poured in from fans and colleagues. Former cast members of The Walking Dead expressed their condolences, describing Kelley as “genuine, driven, and generous.” Directors and co-stars she worked with remembered her professionalism and warm spirit.
Her social media pages were flooded with messages from fans, many of whom shared how Kelley’s performance and public openness about her illness inspired them.
Understanding Diffuse Midline Glioma
This rare form of cancer, which Kelley battled bravely, affects the brainstem or spinal cord and is most often seen in children and young adults. It is particularly challenging to treat due to its location and fast progression.
Symptoms may include:
- Back pain or headaches
- Muscle weakness
- Numbness or tingling
- Difficulty walking or balance issues
- Changes in vision, speech, or mood
Despite advancements in medical research, treatment options remain limited, and survival rates are unfortunately low. Kelley’s story highlights the importance of early diagnosis and the need for continued funding in rare disease research.
Lasting Impact and Legacy
Although Kelley Mack’s career was tragically cut short, her impact was far-reaching. She brought intensity and authenticity to every character she portrayed. Off-screen, she advocated for mental wellness, representation in the film industry, and accessible healthcare.
Her final project, Universal, will likely serve as a lasting tribute to her creative spirit. The film is expected to receive critical attention and may be showcased at upcoming festivals as a posthumous honor.
Beyond her professional accomplishments, Kelley will be remembered as a warm, resilient, and deeply caring individual who touched many lives with her presence.
Final Thoughts
The passing of Kelley Mack is a heartbreaking loss not just to Hollywood, but to anyone who values artistry, bravery, and kindness. At only 33 years old, she had already begun crafting a powerful legacy through her performances, her behind-the-camera work, and her open and honest sharing of her personal health battles.
In remembering Kelley, we celebrate a life of courage, passion, and authenticity. Her contributions to film and television, her openness with fans, and her loving presence in the lives of her family and friends will never be forgotten.
May she rest in peace, and may her legacy inspire others to live creatively and courageously, no matter the obstacles.
