"He said, ‘Mr. Cullen, when I was a kid, you raised me. ... You had such a great impact on my life. I didn't have a father, and you became my father, every day. And I'm very grateful to you for that. You mean a lot to me.'
"I don't think there's any words to express the way I feel now, and did then. Ultimately, it was an obligation and a responsibility to never let that kid down.
"I found out subsequently that there were other young boys at that time in their life that felt the same way, because that's been repeated to me. And without sounding as if I'm — it's more of a humble reaction than it is anything else. It takes me back, and I get a little churn in my stomach when I hear that, and when I think about it, too. It affects me very deeply."
Cullen said the hard-core Transformers fans are to thank for his reprisal of the role in the upcoming big-budget film.
"(The filmmakers) were thinking more Hollywood big names," Cullen said. "They did start to consider the original voice actors because of the enthusiasm and the ... stubbornness of the fan base. God, I'm grateful for those guys," he said.
Cullen was called in to audition for Michael Bay at his offices in Santa Monica, Calif.
He was asked to read a scene with Optimus Prime and Ironhide, a gutsy Autobot who was a close friend of Prime's, also played by Cullen in the original series.
"The script assistant was there, and she started reading for Ironside," Cullen said.
"I said, ‘Excuse me, dear, do you mind if I read it?' Because I actually played this character.'"
Cullen completed the read-through reading for both characters.
Cullen received a callback. This time, Cullen was called to act out a more personal, one-on-one scene.
"The reason for that was, they wanted to find out if I in fact could act," he said.
"Optimus steps out of his normal frame, and becomes ... a little more human."
Shortly later, Cullen heard from his agent that he was again cast as Optimus Prime.
"And I said, ‘Oh, fantastic,' and that's when I started to get involved," he said. "It started getting exciting, and it's remained that way ever since."