Peter Cullen Originally Almost Didn’t Play Optimus Prime in Michael Bay’s Transformers

It is almost impossible to imagine anyone other than the late Peter Cullen delivering the iconic lines of Optimus Prime, but the legendary voice actor was surprisingly not guaranteed the part when Hollywood rebooted the franchise. When director Michael Bay set out to bring Transformers to the big screen in 2007, the studio held open auditions rather than automatically handing Cullen the role he made famous in the original 1980s animated series.

Cullen mentioned the audition episode during an interview with CBR, and said:

When I first auditioned for Michael, a young gal was going to read the lines of the other character. We looked at the script, and it said Ironhide. I actually played Ironhide in the cartoon series as well. So I said, ‘Well, I’d like to do a take of Ironhide, too.’ Michael looked up and said, ‘You can do that?’ I said, ‘Yeah, all the time.

Following the beloved icon’s recent passing at age 85, retrospectives on his career highlight the determination required to reclaim the part, navigating a rigorous casting process to prove that his signature voice belonged on the big screen.

How Peter Cullen Stunned Michael Bay During Transformers Audition

Peter Cullen | Credits: John Manard, licensed under CCA 2.0, via Wikimedia Commons

During his initial audition, Cullen completely blindsided Bay with his classic voice-acting versatility. When an actress in the room prepared to read lines for Ironhide, another Autobot Cullen originally voiced in the G1 cartoon, Cullen offered to read Ironhide’s dialogue as well.

Bay was visibly shocked, asking, “You can do that?” Cullen explained that voice veterans like himself and Frank Welker constantly voiced multiple characters opposite themselves. Cullen immediately dropped into his gruff Ironhide persona, surprising the actress reading with him. While Bay instructed him to stick with Prime’s dialogue, the display left an unforgettable impression.

Bay called Cullen back for two additional auditions before officially awarding him the role. During the process, the director wondered aloud how Cullen’s natural delivery would scale to match a towering, 45-foot CGI titan. Cullen simply suggested, “We’ll just go lower.”

Once production began, the duo forged a seamless creative partnership. Cullen recalled Bay operating like a “general” on set, quickly mastering the lore despite knowing little about the characters beforehand, and grinning broadly in the recording booth whenever Cullen brought the commanding Autobot leader to life.

That legendary collaboration redefined the blockbuster franchise for modern cinema. Cullen went on to anchor the live-action series across multiple blockbuster sequels, leaving behind an immortal legacy as the definitive, soulful heart of the Autobots that generations of fans will never forget.

What is your all-time favorite Peter Cullen quote or memory as Optimus Prime? Let us know in the comments below as we celebrate the extraordinary legacy of a voice acting legend.

Transformers is available to stream on Paramount+.