
Peter Cullen almost voiced Optimus Prime like a shouting Hollywood tough guy. His brother Larry was a Marine Corps captain who served in Vietnam. Cullen has said that before his 1984 audition, Larry told him real heroes don't yell: "Be strong enough to be gentle." That advice became Optimus Prime's voice for more than 40 years.
The Real Marine Behind Optimus Prime's Voice
Peter Cullen has voiced Optimus Prime since the character first spoke on screen in 1984, and by his own account, he did not build that voice alone. It came from one piece of advice his older brother gave him right before the audition.
The Advice Before the Audition
Cullen needed his family's only car to get to the tryout. He mentioned to his brother Larry that the role was for a truck who talked like a hero.
Larry did not tell him how to sound tough. He told him the opposite.
"If you are going to be a leader, be a real leader, not a Hollywood leader with the yelling and screaming," Larry told him, according to Cullen. "Be strong enough to be gentle."
A Real Marine, Not a Movie One
Larry Cullen was not repeating a line from a film. He had lived it.
He trained as an officer at Quantico and served as an infantry officer with K Company, 3rd Battalion, 5th Marine Regiment, in Vietnam.
During Operation Hastings in 1966, Larry faced what Peter has described as roughly a one-in-four chance of survival. He came home with a Bronze Star with Combat "V," two Purple Hearts, and the Combat Action Ribbon, and later made captain, serving at Camp Pendleton.
The Voice That Came From a Brother
Cullen has said that when Larry came home from Vietnam, he was different. Quieter. Calmer.
"He was a man and a superhero to me," Cullen has said.
When the Optimus Prime audition came, Cullen did not invent a cartoon voice from scratch. He drew on what he had watched in his own brother.
"My character in The Transformers for Optimus Prime came from Larry," Cullen has said.
Still the Voice, Decades Later
Cullen kept that same voice through the original 1984 cartoon, the 1986 animated movie, and every live-action Transformers film from 2007's Transformers through 2023's Rise of the Beasts.
More than 40 years after a conversation about borrowing the family car, Optimus Prime still sounds like Cullen's brother telling him to be strong enough to be gentle.
A Second Famous Voice
Cullen is also the longtime voice of Eeyore in various Winnie the Pooh productions, a much gentler role he has voiced alongside Optimus Prime since the late 1980s.
Frequently Asked Questions
Who is the voice of Optimus Prime?
Why does Optimus Prime sound the way he does?
Was Peter Cullen's brother really a Marine?
Does Peter Cullen voice any other famous characters?
How long has Peter Cullen voiced Optimus Prime?
Verified Fact
Verified Aug 11, 2026 · 3 sources checked
Source: We Are The MightyShow verification details
Claims checked
- Larry Cullen was a Marine Corps captain who served in Vietnam
- Larry's advice "be strong enough to be gentle" shaped Optimus Prime's voice, per Peter Cullen's account
- Peter first voiced Optimus Prime in 1984 and continued for over 40 years
Sources: We Are The Mighty, TFwiki, Wikipedia
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