On TV, he's the awkward, brainy middle child in the sit-com "Malcolm In The Middle."
On the big screen, he's agent Cody Banks, a not-so-suave junior James Bond.
In a few short years, the kid with the cute face and sparkling blue eyes has become one of Hollywood's most bankable teens.
His salary for "Agent Cody Banks" was somewhere around $2 million – pretty good for Muniz, who just turned 18 this month. Correspondent Maureen Maher reports on this story that first aired last June.
It probably comes as no surprise that a young actor who makes millions playing teen roles is not like a normal teenager.
What is surprising is what he himself thinks of teenagers.
"I hate teenagers, you know what I mean," says Frankie. "I think they are the most annoying people on the planet."
Call him the anti-teen.
"No parties. I've never been to a party with teenagers. I think teenagers are so stupid with the choices they make. And I hate peer pressure like smoking, drinking, any kind of drug," says Frankie, who claims he's never tried cigarettes or drinking.
He has, however, made some excellent career choices - winning critical acclaim for his role in "Malcolm In The Middle" and for his role in the film "My Dog Skip." His first teen comedy, "Big Fat Liar," was also a surprise box office hit.
Does this teen superstar think he is more grown up than other kids his age?
"Physically no," says Frankie, laughing. "But like maturity-wise, and you know, I definitely think so."
In fact, Frankie goes out of his way to avoid the typically embarrassing teenage situations his characters often find themselves in: "I know some kid actors who are like, 'Oh, I'd much rather be going to high school.' Why?"
Unlike his character "Malcolm," Frankie hasn't set foot in a classroom since the sixth grade, when he began home schooling.
"Why? I'm going to like the Emmy's, the Golden Globes, the Grammy's," says Frankie. "I'm meeting all my favorite celebrities. I have the opportunity to do that, and why would someone pass that up to go to a high school prom?I'm extremely happy and I wouldn't trade it for anything."
Surprisingly, Frankie didn't grow up wanting to be a Hollywood star. He was raised in the tiny town of Knightdale, N.C. – population, 6,200 people. His mother was a nurse; his father a restaurant manager. His passion was basketball and soccer, but at 8, Frankie decided he wanted to try his hand at acting.
His first role was playing Tiny Tim in a local stage production of "A Christmas Carol."
"I did it and I liked it but I didn't know I wanted to be an actor," says Frankie.
He continued anyways, starring in commercials before picking up small roles on TV and eventually moving to California with his mother.
"I still don't know if I want to be an actor," says Frankie. "I still don't know if that's what I want to do when I grow up."
Does he want to do serious roles? Does he dream of doing Shakespeare?
"I don't dream of doing Shakespeare. I want to do serious roles, and we've talked about it, all my people," says Frankie.
His people? "Why did I say that," says Frankie, laughing. "I seem like the biggest jerk right now. I am very lucky, and that's it."
But Frankie says he's no dummy when it comes to managing his newfound wealth.
"I'm good with my money, like not spending it and stuff like that, but it can go fast," says Frankie.
That doesn't mean, however, that Frankie isn't having a little fun.
"I bought a couple of cars," he says, including the $100,000 Jetta from the movie "The Fast and the Furious," and a rare Porsche that cost him $250,000.
Soon, he'll be able to add a few more hot wheels to his collection. Last summer, when other high school kids his age will be making minimum wage, he was making the sequel to "Agent Cody Banks," which will be released in March 2004.
His paycheck? A reported $5 million.
Does he consider himself wealthy? Not enough, he says.
"I always said when I got to my first million, we shouldn't be talking about money, but when I got to my first million, that I was done. I was rich," says Frankie. "I'm waiting for a hundred, and then I'll be done … because that's enough."