Kelley Mack – Cause of Death and TV Career at 33
Kelley Mack, an actress best known for her role as Addy on AMC’s The Walking Dead, died on August 2, 2025, at the age of 33. Her family confirmed the news through social media posts on August 4, asking for privacy during their time of grief. Mack also appeared in episodes of 9-1-1 and Chicago Med, building a career across both television and independent film.
Born Kelley Lynne Klebenow in Cincinnati, Ohio, she adopted the stage name Kelley Mack and worked steadily in the entertainment industry for over a decade. Her death has prompted an outpouring of tributes from fans and former colleagues, who remember her as a promising talent taken far too soon.
While initial reports provided few details, subsequent announcements from representatives and family members clarified that Mack had been battling a rare and aggressive form of cancer. The following article compiles the verified facts about her life, career, and passing.
Who Was Kelley Mack?
Kelley Lynne Klebenow
July 10, 1992
August 2, 2025
Addy on The Walking Dead, appearances on 9-1-1 and Chicago Med
Key Insights About Kelley Mack
- Her death was announced via family statements on Instagram and Facebook on August 4, 2025.
- Her most recognizable role was Adeline (“Addy”) in Season 9 of The Walking Dead.
- She also appeared in episodes of 9-1-1 and Chicago Med, though specific episode details are not widely documented.
- She was born and raised in Cincinnati, Ohio.
- She worked as an actress, producer, and voice-over artist.
- The cause of her death was later confirmed as a rare brain and spinal cord tumor.
Snapshot Facts
| Category | Information |
|---|---|
| Known For | Actress, producer, voice-over artist |
| Birthplace | Cincinnati, Ohio |
| Age at Death | 33 |
| Social Media | @itskelleymack (Instagram) |
| Real Name | Kelley Lynne Klebenow |
| Death Announced | August 4, 2025 |
| Cause of Death | Diffuse midline glioma (rare astrocytoma cancer) |
What Was Kelley Mack’s Cause of Death?
Kelley Mack died as a result of a diffuse midline glioma, a rare, aggressive tumor of the central nervous system that can affect the brain or spinal cord. Her family and representatives initially did not disclose her illness, but by mid-August 2025, several authoritative sources reported the specific diagnosis (IMDb News, ABC News, Biography.com).
Mack was diagnosed in January 2025 after experiencing persistent lower back pain and shooting pains in her legs (ABC News, Biography.com). She revealed that an “abnormal mass” was found on her spine, and a subsequent biopsy resulted in the loss of use of her right leg and most of her left leg, requiring a walker and wheelchair.
Her agent, Julie Smith, confirmed to USA Today that her death followed a battle with glioma of the central nervous system (Newsweek). Despite the cancer diagnosis, her representative stated that her death was “very unexpected” (People). She passed away peacefully at her home in Cincinnati, Ohio, surrounded by her mother, Kristen, and her aunt, Karen.
Diffuse midline gliomas are a rare category of brain and spinal cord tumors that are typically aggressive and difficult to treat. They occur most often in children but can affect adults as well. The tumor’s location in the midline structures of the central nervous system makes surgical removal challenging.
Which TV Shows Did Kelley Mack Appear In?
Kelley Mack’s Role on The Walking Dead
Mack played Adeline (“Addy”) in Season 9 of The Walking Dead. Her character was a member of the Hilltop community, appearing in multiple episodes during the season. This remains her most widely recognized television role.
Did Kelley Mack Appear on 9-1-1?
Yes, Mack had a guest role on the procedural drama 9-1-1. However, specific details about her character and the episode in which she appeared have not been widely documented in available sources.
Was Kelley Mack on Chicago Med?
Mack appeared on Chicago Med in Season 8, portraying a character named Penelope Jacobs. This role has been confirmed by both IMDb and People.
Other Notable Works
Beyond her television guest spots, Mack also appeared in the independent horror film Broadcast Signal Intrusion as the character Alice. She is also set to appear posthumously as the character Ricky in an upcoming Universal project (People). In addition to acting, she worked as a producer and voice-over artist.
While Kelley Mack’s filmography is not extensive, her roles on three major network and cable series — The Walking Dead, Chicago Med, and 9-1-1 — demonstrate steady work across the television industry during the late 2010s and early 2020s.
When Did Kelley Mack Die?
Kelley Mack died on August 2, 2025, a Saturday evening. Her family announced the news on August 4, 2025, via a heartfelt message on her Instagram account and through CaringBridge, a site used to share health updates.
Timeline of Key Events
- July 10, 1992 — Born in Cincinnati, Ohio as Kelley Lynne Klebenow.
- Early 2010s — Began acting, credited professionally as Kelley Mack.
- 2018-2019 — Portrayed Addy on AMC’s The Walking Dead (Season 9).
- 2019-2021 — Guest appearances on 9-1-1 and Chicago Med.
- January 2025 — Diagnosed with diffuse midline glioma after experiencing back and leg pain.
- August 2, 2025 — Died peacefully at home in Cincinnati, Ohio.
- August 4, 2025 — Family announces death via social media.
- August 16, 2025 — A “recognition and remembrance” service held in Glendale, Ohio.
What Is Known About Kelley Mack’s Last Photo and Social Media?
Mack maintained an active social media presence under the handle @itskelleymack on Instagram and had a corresponding Facebook page. Following her death, her family posted a memorial message on both platforms. The content of her last public photo has not been described in detail by major news outlets, though fans have shared and commented on her recent posts in tribute.
Her family’s statements on CaringBridge and social media constitute the primary official sources of information, as they requested privacy during their bereavement.
What Remains Uncertain About Kelley Mack’s Death?
| Established Information | Information That Remains Unclear |
|---|---|
| Mack died on August 2, 2025, at age 33. | The exact cause of death was initially unconfirmed, though diffuse midline glioma has since been reported by multiple outlets. |
| Her legal name was Kelley Lynne Klebenow. | Her birth date is listed as July 10 on Wikipedia, but as January 10 on Fandom — a common discrepancy in fan-maintained wikis. |
| She played Addy on The Walking Dead and appeared on 9-1-1 and Chicago Med. | Specific episode numbers and character names for her roles on 9-1-1 and Chicago Med are not widely documented. |
What Does Kelley Mack’s Death Mean for Her Legacy?
Kelley Mack’s passing at a relatively young age, with no prior public knowledge of her illness, has left fans of genre television in mourning. Her career, while not sprawling, earned her a dedicated following within the Walking Dead fandom. The confusion in birth dates between Wikipedia and Fandom underscores the challenge of verifying biographical details after a sudden death, particularly when official sources are limited.
The social media tributes from her family serve as the primary source of official information, highlighting the need for a centralized, authoritative summary of her life and work. Her upcoming posthumous appearance in a Universal project ensures that audiences will see her on screen one last time.
What Are the Sources for Information About Kelley Mack?
“It is with indelible sadness that we are announcing the passing of our dear Kelley.”
— Family statement via Instagram (@itskelleymack)
“Kelley passed peacefully on Saturday evening.”
— Family statement via Facebook
“Kelley Lynne Klebenow (July 10, 1992 – August 2, 2025), known professionally as Kelley Mack, was an American actress.”
— Wikipedia
“Kelley Mack (1992-2025) was an actress, producer and voice over artist.”
— IMDb
What Happens Next?
A second celebration of life is planned for Los Angeles at a date yet to be determined. Fans and colleagues are encouraged to monitor official family announcements for any future memorial details or tributes from co-stars. As new information becomes available from verified sources, the biographical record for The Walking Dead actress Kelley Mack dies at 33 will be updated accordingly.
Frequently Asked Questions About Kelley Mack
How old was Kelley Mack when she died?
She was 33 years old.
What was Kelley Mack’s real name?
Kelley Lynne Klebenow.
Did Kelley Mack appear on 9-1-1?
Yes, she had a guest role, though episode details are not widely documented.
Was Kelley Mack on Chicago Med?
Yes, she appeared in Season 8 as Penelope Jacobs.
Who is Addy in The Walking Dead?
Addy (full name Adeline) is a character in Season 9 portrayed by Kelley Mack.
Where was Kelley Mack born?
Cincinnati, Ohio.
What was the cause of Kelley Mack’s death?
Diffuse midline glioma, a rare and aggressive tumor of the central nervous system.
Is there a memorial planned for Kelley Mack?
A remembrance service was held in Glendale, Ohio, on August 16, 2025. A Los Angeles celebration of life is still being planned.
Does Kelley Mack have a Wikipedia page?
Yes, she is listed on Wikipedia under her legal name, Kelley Lynne Klebenow.
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