Even if you don’t know the name Peter Cullen, you’ve likely heard his voice as Optimus Prime throughout the Transformers franchise. As the supreme commander of the Autobots in their fight against the Decepticons, Cullen has played the role since the original 1984 animated series and continued through numerous films and shows. His deep, resonant voice made him an iconic legend and turned Optimus Prime into one of the most loved characters in animation. Once you’ve heard Cullen bring Optimus Prime to life, it’s hard to imagine anyone other than him delivering the iconic lines. But when director Michael Bay decided to bring Transformers to the big screen in 2007, the voice actor also known as Eeyore in the world of Winnie the Pooh had to audition. Clearly, that went well and he ultimately won Bay’s approval, leaving a lasting impression on the filmmaker. The filmmaker recently spoke to TMZ, where he recalled the first time he heard Cullen do his thing: I must tell you. I can’t say that word, I can’t say the F-word. I’m like, ‘No Fucking way that man has that voice!’ I was awestruck. The chills went down my spine. True story. We filmed [the voice actors] to look for their mouth movements, so that we could use the animation. And I remember looking to someone who has worked at Bay Films for quite a long time. And I remember looking, and I’m like, ‘Oh my god. Oh my god.’ It was amazing.I wouldn’t consider myself a hardcore Transformers fan. I'm more of a casual and occasional viewer, having seen some of the live-action movies and episodes of the animated series. But even so, I would count Peter Cullen’s performance as Optimus Prime to be the highlight across the franchise. It’s easy to understand why the Bad Boys director, who has been the man in charge of the Transformers film series, would get chills hearing that perfect partnership between character and voice actor. Peter Cullen reportedly passed away from cardiac arrest on August 26th at the age of 85. The Armageddon director learned of the news when he received texts and then took time to absorb before he ultimately cried over the loss. Billions of people have heard this man’s voice, and his legacy will live forever in the work that he’s done. Even if you don't enjoy the Michael Bay-era live-action Teenage Mutant Ninja Turtles movies, it’s impossible to argue against his decision to lock in Peter Cullen as Optimus Prime for his Transformers films. It’s a performance so iconic that it was no surprise that Chris Hemsworth was nervous about living up to the incredible foundation laid by his predecessor when it came time to voice the character for the animated Transformers One. Thankfully, playing a more youthful version meant the Thor actor didn’t have to mimic what Cullen had done or convey the evolution of Optimus Prime’s voice and could instead find his own approach. The Transformers: The Movie is celebrating its 40th anniversary and there is a brand-new 12-minute animated short, Optimus Prime: Awakening, that features the final original voice performance from Cullen. But his loss makes you wonder what will happen with the character of Optimus Prime in the future. Whatever decision gets made, the actor will forever have a legacy that can be loved and appreciated by fans and generations to come.