Kelley Mack – Cause of Death, Age, and Career Highlights

Kelley Mack, the American actress known for her role as Addy in The Walking Dead cast, died on August 2, 2025, at the age of 33. Her family confirmed the news in a social media post, describing her passing as peaceful and surrounded by loved ones. The cause of death was diffuse midline glioma (DMG), a rare and aggressive form of cancer affecting the central nervous system.

Born Kelley Lynne Klebenow in Cincinnati, Ohio, Mack built a career spanning television, film, and voice acting. She appeared in popular series such as Chicago Med and 9-1-1, and contributed to the animated feature Spider-Man: Into the Spider-Verse as a voice double. Her death has prompted tributes from fans and colleagues within the entertainment community.

At the time of her passing, Mack had 35 acting credits and five producer credits to her name. She was also executive producing the unreleased film Universal. Her last television commercial was for Rakuten, which she filmed alongside her mother, Kristen Klebenow.

What Was Kelley Mack’s Cause of Death?

Overview

Key Insights

• Kelley Mack died at age 33, just weeks after her 33rd birthday.
• Her most recognized role was as Addy (Adeline) in The Walking Dead season 9.
• She had a versatile career spanning television, film, and voice-over work.
• Her family announced her death on Instagram, stating she passed peacefully.
• The cause of death was diffuse midline glioma, a rare and aggressive tumor.
• She completed proton radiation treatment in April 2025.
• Wikipedia and IMDb have been updated to reflect her death date.

Snapshot Facts

How Old Was Kelley Mack? Biography and Personal Details

When was Kelley Mack born?

Kelley Mack was born Kelley Lynne Klebenow on July 10, 1992, in Cincinnati, Ohio. She grew up in the Cincinnati area and later pursued acting professionally, adopting the stage name Kelley Mack.

What is Kelley Mack’s Wikipedia page?

The Wikipedia entry for Kelley Mack confirms her birth and death dates, her name change, and her role as Addy in season 9 of The Walking Dead. It also lists her as an American actress with additional credits in film and television. The page was updated shortly after her death to reflect her passing on August 2, 2025.

What was Kelley Mack’s early life like?

Limited information is publicly available about Mack’s early life and education. She was born and raised in Cincinnati, Ohio, and later moved to Los Angeles to pursue an acting career. Her professional name, Kelley Mack, differs from her legal birth name, Kelley Lynne Klebenow.

What TV Roles Did Kelley Mack Play?

What character did Kelley Mack play on The Walking Dead?

She portrayed Adeline, also referred to as Addy, in season 9 of AMC’s The Walking Dead. The character was part of the Whisperer storyline, and Mack appeared in multiple episodes during that season. Her performance was well received by fans of the series.

Did Kelley Mack appear on Chicago Med?

Yes, she had a role on Chicago Med. According to available records, Mack played Penelope Jacobs in Season 8 of the NBC medical drama. Specific episode numbers are not widely detailed in public sources, but her appearance has been confirmed by multiple outlets including ABC News.

Did Kelley Mack appear on 9-1-1?

Kelley Mack is also known for a guest appearance on the procedural drama 9-1-1. She played Penelope Jacobs in that series as well, according to ABC7. Specific episode details are limited, but her credit is listed in official databases.

What other projects did Kelley Mack work on?

Mack had a diverse career that extended beyond live-action television. She worked as a voice-over artist and contributed to animated projects. Her last known voice role was in Spider-Man: Into the Spider-Verse, where she served as a voice double for the character Gwen Stacy. Her final television commercial was for Rakuten, which she filmed with her mother.

What Were the Key Events in Kelley Mack’s Life?

1. July 10, 1992: Born as Kelley Lynne Klebenow in Cincinnati, Ohio.
2. Early 2010s: Began acting career, likely in short films and local productions.
3. 2018–2019: Played Addy in season 9 of The Walking Dead.
4. 2020 or after: Appeared in Chicago Med as Penelope Jacobs (season 8).
5. 2021 or after: Guest role on 9-1-1 as Penelope Jacobs.
6. 2024–2025: Diagnosed with diffuse midline glioma; completed proton radiation treatment in April 2025.
7. August 2, 2025: Passed away peacefully at age 33, surrounded by family.
8. August 3, 2025: Family announces death via Instagram; Wikipedia and IMDb updated.
9. August 16, 2025: Memorial service held at Glendale Lyceum in Glendale, Ohio.

What Is Confirmed and What Remains Unclear?

What Impact Did Kelley Mack’s Death Have?

Kelley Mack’s death at a young age prompted an outpouring of tributes, especially within The Walking Dead community. Fans shared memories of her character Addy and expressed condolences to her family. Her limited but memorable television roles, combined with her behind-the-scenes work as a producer, illustrate a career that was still developing at the time of her passing. The absence of an official obituary from major outlets initially led to uncertainty, though her family’s social media statement and subsequent reporting from sources such as Biography.com and ABC News provided clarity.

Mack’s diagnosis with diffuse midline glioma — a rare and aggressive form of astrocytoma cancer — was disclosed in earlier reports. She had described the condition as an “extremely rare type of astrocytoma cancer” and had undergone treatment in Cincinnati for several months before her death. The tumor was found on her spine after she complained of persistent lower back pain and shooting pains in her legs. The biopsy surgery ultimately resulted in the loss of use of both legs, requiring her to use a walker and wheelchair.

What Did Kelley Mack’s Family and Colleagues Say?

“It is with indelible sadness that we are announcing the passing of our dear Kelley. Such a bright, fervent light has transitioned to the beyond.”

— Family statement posted on Kelley Mack’s Instagram page

“Kelley Lynne Klebenow (July 10, 1992 – August 2, 2025), known professionally as Kelley Mack, was an American actress. She played Addy in season 9 of The Walking Dead.”

— Wikipedia entry for Kelley Mack

Her family also confirmed that she passed peacefully on Saturday evening, August 2, 2025, surrounded by her mother, Kristen Klebenow, and her aunt, Karen. A “recognition and remembrance” of life was held on August 16, 2025, at the Glendale Lyceum in Glendale, Ohio. A second celebration of life is planned for a future date in Los Angeles for friends and colleagues.

What Is Kelley Mack’s Legacy?

Kelley Mack leaves behind a body of work that spans television, film, and voice acting. Her role as Addy in The Walking Dead remains her most widely recognized performance, but her appearances on Chicago Med and 9-1-1, along with her work on Broadcast Signal Intrusion and Spider-Man: Into the Spider-Verse, demonstrate a versatile talent. For those seeking more information, actress obituaries provide additional context on her life and career.