Peter Cullen’s official cause of death has been confirmed as cardiac arrest, according to newly obtained death certificate records.
The Transformers voice legend, 85, died on August 26 at his Los Angeles home, his representative had previously confirmed. The outlet first reported the certificate’s details, and PEOPLE obtained the document on Wednesday. The Canadian-born actor’s death certificate lists sudden cardiac arrest as the primary cause, with respiratory arrest noted as the immediate underlying cause.
The medical document also cites multiple significant secondary conditions that contributed to his passing. These include cerebellar metastasis, indicating cancer that had spread to the cerebellum region of the brain, alongside hypoxia, chronic obstructive pulmonary disease, hypertension, and hyperlipidemia.
Cullen’s commanding baritone defined Optimus Prime across 40 years of the Transformers franchise, making him one of the most recognizable voices in pop culture history. He first assumed the role in 1984 for the original animated series The Transformers, creating a vocal performance that would anchor the character through generations of television series, animated films, and live-action blockbusters.
The voice actor famously drew inspiration for Optimus Prime’s noble cadence from his older brother Larry, a decorated US Marine Corps captain who served in the Vietnam War. Larry had advised Cullen before his audition to portray a hero who was “strong enough to be gentle” rather than loud and aggressive, guidance that became the moral foundation of the beloved Autobot leader.
Cullen reprised the role in the 1986 animated feature The Transformers: The Movie before returning to headline Michael Bay’s live-action film series beginning in 2007. He continued voicing Optimus Prime in more recent franchise installments including Bumblebee in 2018 and Transformers: Rise of the Beasts in 2023.
Beyond his iconic work in the sci-fi franchise, Cullen held a special place in Disney audiences’ hearts for his portrayal of the gloomy, lovable donkey Eeyore in The New Adventures of Winnie the Pooh and various spin-off projects. His extensive voice acting resume also included Monterey Jack in Chip ‘n Dale: Rescue Rangers and the guttural vocal effects for the alien hunter in the 1987 action classic Predator.
News of Cullen’s passing last month prompted an outpouring of tributes from colleagues, fellow voice actors, and fans across multiple generations. Many celebrated a performer whose voice had anchored childhood memories for millions worldwide, from Saturday morning cartoon viewers to multiplex audiences experiencing his work across four decades of evolving entertainment formats.
The death certificate’s revelation of cerebellar metastasis adds a previously undisclosed dimension to the health challenges Cullen faced in his final period, alongside the documented respiratory and cardiovascular conditions.