Transformers star Peter Cullen died from cardiac arrest … TMZ has learned.

TMZ obtained the death certificate for Peter, who died on August 26, 2026, at his Los Angeles home in the Toluca Lake neighborhood. The immediate cause was cardiac arrest due to respiratory arrest.

 The underlying cause was listed as malignant neoplasm of the lower lobe of the lungs.

Peter, best known for voicing Optimus Prime in the “Transformers” franchise for decades.

He is scheduled to be buried at Forest Lawn on September 9. Peter’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.’”