Since Harnell had no awareness of cartoon stars, he didn’t know the level of talent surrounding him on his first animated series, Animaniacs. Courtesy of Cartoon Network. © Warner Bros.

NC: What's the most challenging job you think you've ever had?

JH: The most challenging situation for me in this career was the worst job I ever had. My agent called me one day and said to be in Hollywood the next morning for a movie voice match, [which turned out to be for] John Malkovich. Well, I don't do John Malkovich. He told me it was probably just a little thing, I would be fine, but I really wasn't comfortable with it. He kept pushing saying, "Trust me, man, you can nail it."

So I walk in to the session, 12 people in there sitting behind a desk, and the director stood up and said, "Here's the guy who's going to save our frickin' life." He tells me John is in Tunisia or something and the movie has a release date and we desperately need this and my agent told him I was the guy. This is for a voice match, and the absolute worst case scenario for a voice match is a quiet scene where the actor speaks a line, then you speak a line (as him) then the actor speaks a line, with no breaks. That was exactly what this was: playing poker in a quiet room, doing his own voice, no other noise to mask it.

Rob Paulsen.

Even if I had done a stellar impression, it would have been challenging. I'm feeling the sweat run down my back now and these people are looking at me and I didn't know if I should say I don't really do this. So I give it a shot, and I'm standing there with my back to them and I say the line… I think they ended up using it but I knew it definitely wasn't a home run and it was the only session, thankfully, that I've ever walked out of really angry. I called my agent and said don't ever put me in this position again -- never ever. I wasn't informed and I wasn't prepared.

NC: You've given us basically your philosophy in the course of this interview. Any remaining sage advice that you would give the young pups just starting out?

JH: Main thing: be a sponge, keep your ears open, keep developing, find what you can do well and exploit that; find what you can't do and don't include that. Don't put anything on your demo that isn't a home run, and if you don't think it is, no one else is going to. So if that means being super-critical and sitting and sifting through everything until you find a combination that you're really happy with, go with it. Have a smile on your face and a song in your heart and try to make it really easy to have you in the room. When you're there, devote yourself 100 percent and give it everything you have. Also, when you're auditioning, keep in mind that the people you're auditioning for have already heard 50 of the "best" auditioning for your copy, so whatever you can do to make it stand apart (don't go crazy with it necessarily); but, particularly in the beginning, if there's something you can do, add a joke or change it up a little to make yourself stand out.

NC: Well, on that note, it was great having you.

JH: It was even better being had!

Nancy Cartwright is best known as the voice of spiky-headed Bart Simpson on The Simpsons. She has voiced dozens of cartoon characters in a career that has spanned more than 20 years. Currently, she can be heard as the voice of Rufus the Naked Mole Rat on Disney's Kim Possible and Todd Daring in Disney's The Replacements. To learn more about Nancy's career, listen to her audio book My Life as a 10-Year-Old Boy.