Legendary Voice Actor Peter Cullen’s Cause of Death Released

Peter Cullen, the voice of Optimus Prime in the Transformers franchise, passed away on August 26, 2026. The cause of death, per TMZ, is determined to have been cardiac arrest.

The media outlet obtained a death certificate revealing as much and further stating that the cardiac arrest was due to respiratory arrest. Peter passed away at his home in Los Angeles. He was 85 at the time of his death.

Cullen, who was nominated for a Daytime Emmy Award in 2011 for his voice work in the animated series Transformers Prime, is reported (per TMZ) to have had an underlying case of malignant neoplasm of the lower lobe of the lungs.

He was buried earlier this month at Forest Lawn Memorial Park in Hollywood Hills.

Upon his passing, Cullen’s family told TMZ, “Peter Cullen passed away peacefully, surrounded by his loving family – and held in the hearts of his many friends and countless fans worldwide. His family asks that you honor his remarkable legacy by serving your communities and leading others with compassion, integrity, and loyalty and always remember ‘be strong enough to be gentle.’”

Cullen’s recognizable voice career wasn’t limited to voicing Optimus Prime. Other notable voice roles included playing Winnie the Pooh’s Eeyore, Monterey Jack in Chip ‘n Dale: Rescue Rangers, various episodes and voices in The Smurfs, Alvin and the Chipmunks, G.I. Joe, Scooby-Doo, and dozens of other TV shows and movies.

Earlier this month, Cullen made his final appearance as a voice actor (posthumously) in the animated short, Optimus Prime: Awakening. The 12-minute film has been dedicated to Cullen’s memory.

In a 2019 interview with the Associated Press, Cullen said of auditioning for his memorable role as Optimus Prime, “You’re always auditioning for something in animation that’s a little off of the norm.”

The voice actor is survived by his four children.