Transformers: The Last Knight features the latest clash of Cybertronian combatants Optimus Prime and Megatron, who have been battling it out since the 1984 animated series and the 1986 animated movie. The "Generation One" Transformers may have started it all, but the franchise has evolved in numerous directions over the 30+ years since. A lot of things have changed, but some tenets have actually stayed the same, like the fact that Optimus Prime will always emerge as a hero, Megatron will always attempt to take him down, and that Peter Cullen and Frank Welker will always be the iconic voices of those fan-favorite characters.

To celebrate Transformers: The Last Knight, now available on Digital HD and coming to Blu-ray/DVD on September 26th, I was able to speak to both Cullen and Welker, together. I'm thrilled that they were paired for this interview since, much like the process of voice-acting itself, their ability to play off of each other allowed for a very entertaining experience for yours truly. We talked about their long history of playing the lead characters, how both Optimus and Megatron have evolved over the years, and what it was like performing the role for director Michael Bay in the latest film from Paramount Pictures. For fans of both Cullen and Welker, it's a must-read since they tell some fantastic tales from their many years in the recording booth.

While most of their fans likely know the duo from their Transformers work, Cullen and Welker actually go back even further than that:

Peter Cullen: We go back to a cartoon series called Mighty Man and Yukk. [1979]

Frank Welker: Ah yes, yes, yes.

Cullen: And that’s when I first met Frank. But Frank had met me many, many times because he used to go to hockey games and I served hot dogs. [laughs]

Welker: I was a big fan of Peter’s. I used to watch him on the Sonny and Cher show when he did that little character up front. I did not know it was Peter at the time, but when I heard him doing that…

Cullen: The little man in the ball?

Welker: Yeah, the little man in the ball and those sound effects. I thought, whoever this is, I think I’m going to retire, he’s just too good.

Cullen: I was brought into the studio and they showed me an animated ball that was being poked with a stick from the inside, and the ball would open up. They said, “Try to think of a voice, or something. He’s kind of like a little gremlin inside the ball … Then, as an announcer, I want you to say, ‘From Television City in Hollywood, ladies and gentlemen, it’s the Sonny & Cher Show!’, okay?” So I do Take One. They kept that recording for the next four years. I never had to do it again.

[You can get a look at Cullen's work in the show's intro here.] Since Cullen and Welker have been around since G1, I was curious to know their thoughts on the ever-evolving designs of their characters: 

Welker: I think for me, Megatron, for obvious reasons, is my favorite, followed closely by Soundwave. But it is interesting to see the changes from the animated version, the G1 version, which was pretty basic, to now with all of the technology and incredible things that they’re doing with design and color and sound … it’s a really interesting—excuse the pun—but true transformation. I’ve enjoyed watching it. I’ve actually had to change my voice to match the size and the differences in the characters.

Cullen: Frankly speaking, you’ve mastered that really well, from 1984 to the present, especially the feature film of late. You kept the character, it’s the exact same character, it just got [more] evil. Eviler, if that’s a word. Meanier. [laughs]

But after all those years playing the same roles, how do they keep their performances fresh?

Cullen: First of all, the writing is consistent, and always has been. For Optimus, they follow the guidelines of character traits. There’s still the honesty, integrity, honor, dignity, the sense of trustworthiness and compassion. Those qualities have not changed, and that makes it relatively easy for Optimus to maintain a consistent level of character. Not speaking for Frank, but evil is as evil does.

Welker: Yeah, we do have that to hang our acting hats on, the epitome of evil and the epitome of good. Changes through the physicality of the characters, obviously Michael Bay wanted something he felt would work with the size of Megatron. It was so fun to work with him on it because he encouraged me to ad lib and to throw in what I saw. The first thing he said when I walked in, he said, “Well, what do you hear for this guy?” As an actor, it’s so much more enjoyable to have a collaborative type effort. He would encourage us to ad lib on the basic lines that were there. That allowed me to become angry and throw things in and make sounds or whatever, and he appreciated that. That helped me get into that character.

Obviously they've done both Transformers movies and TV shows. Here's the biggest difference between those performances:

Cullen: One of the most obvious, for me, was when we did the cartoon series, we’d all be together in a small recording booth. It would be 8 to 10 characters staring into the glass with the director on the other side with the sound men. With the feature film, it was always working one-on-one with Michael Bay, the sound engineer, and a camera on your lips. So, yes, they were very, very different.

Welker: As Peter was saying, when you have a cast, you kind of play off each other. You can build … almost like a play, because obviously you read it as a play, so you have this nice interaction. When we did the series, standing next to Peter was always a benefit because you really get into it. You’re going hand-to-hand, but physically, you get the feeling of that person being there.

However, when you go to the feature, for what we do, you can’t really do it together. You need to do it independently to make it possible, technically, to get the voice and the sound you need. It becomes a different acting exercise, two different disciplines. They’re both really enjoyable and I’ve kind of learned to enjoy being by myself, as ridiculous as that sounds, because you have to create this world around you and it takes a lot more. I think it’s just two different disciplines, but it’s always better to work with fellow actors; it feels good.

Cullen and Welker, who are both in their 70s, still play around, doing silly voices and riffing off of each other in character after character. Clearly, they still enjoy the craft. So I wanted to know if there were any times that the script or their emotions really took over their performances. I was not disappointed. 

Welker: I was doing a remake and it involved a bunch of wolves. I was in the middle of this wolf fight [growls and snarls], just going crazy. And, son of a gun, I threw my jaw out. It was such severe pain for maybe 15 seconds and then it popped back in. I thought to myself, “What was that?!” I thought maybe Cullen snuck in and got me! That was the weirdest thing that ever happened to me during a recording session. Believe it or not, it was literally like 10, 15 seconds and I was back working again; the next day, it felt like somebody had hit me with a bat in the jaw.

Cullen: I remember I had just finished King Kong [1976, and 1986's King Kong Lives, using his vocalizations], and I had been coughing up blood because it demanded so much [roars]. Anyway, a couple hours after that, I had to go and do Optimus Prime. I don’t know how I pulled it off, but I think Optimus Prime sounded about an octave-and-a-half higher than he normally did.

With on-the-job hazards like that, you might wonder how Cullen and Welker have stayed healthy in this business for so long: 

Welker: Early in my life, I probably abused my voice more than I should have. It is an instrument. You need to take care of yourself. If you have a session the next day, go to bed early, do vocal warm-ups on the way to the studio, that’s just about all you can do.

Cullen: My mom used to say, “Peter, don’t do this, you’re going to ruin your voice! It’s going to stay like that!” But when I was an acting student, I studied under an operatic coach named Bernard Diamant from New York. He described the basic instrument, as we all have, the human voice. I was particularly impressed with a remark that he made: A baby, when it’s born, has the most perfect vocal ability. Opera singers study to get back to that for years through the use of your diaphragm, the expansion of air in your chest and lungs, the use of tonal cavities that are built into your upper chest and your head.

All of that training has obviously paid off. You can hear both Cullen and Welker's wealth of voice talent on display in the new Transformers: The Last Knight home video:

Welker: If you get any of the Transformers on the Blu-ray version, which I just did; I finished my house and made a little theater in there with all my sound equipment. When you use the Blu-ray, Peter will actually take the dust off your wall and the paint begins to crack. That’s the kind of voice this guy has. The color and the sound, oh my gosh.

For more on our coverage of Transformers: The Last Knight be sure to check out these recent write-ups:

• Exclusive: ‘Transformers: The Last Knight’ Concept Art Reveals Ancient History
• Exclusive: ‘Transformers: The Last Knight’ Clip Sees Michael Bay Direct Explosive Action