Peter Cullen dead: 'Transformers' Optimus Prime voice was 85

To play Optimus Prime, Cullen said he channeled the spirit of his older brother, Larry, a decorated U.S. Marine who served in Vietnam from 1965-68.

“When he came home, I could see a change. He was quieter and he was a man and a superhero to me,” he said in 2006. “I watched him and listened to him. I’d never had an opportunity to do a superhero, and when that came, [that voice] just came right out of me, and I sounded like Optimus.”