How Chris Pratt Went From Super Goof to Superhero of the ‘Galaxy’

— -- Actor Chris Pratt never thought in his “wildest dreams” he would be asked to set the tone for a Marvel blockbuster film, cast in the lead role for “Guardians of the Galaxy.”

“Marvel did not show me a script,” Pratt said in an interview with ABC’s Chris Connelly for “Nightline.” “They’re like, ‘Hi, we’re Marvel.’ And I was like, ‘Hi, I’ll do anything.’ And they’re like, ‘Yeah, you will.’”

In “Guardians,” Pratt plays a shambling, self-deprecating hero-dude named Peter Quill, who leads a rag-tag multi-species team on a “bring me the orb” mission.

It’s Marvel’s first film not based on a wildly popular comic series. It’s also the first of Marvel’s films to be set away from planet Earth, and it’s fully backed by The Walt Disney Company, ABC News’ parent company.

Pratt is hardly a household name, best known for his role as the doofus-y Andy Dwyer on the TV series, “Parks and Rec.” In fact, director James Gunn was skeptical at first about casting him in the lead role.

“Somebody first suggested him to me, I thought, you got to be kidding me. This chubby guy from ‘Parks and Rec'?” Gunn said. “There’s no way I’m going to make that guy the star of my movie.”

But as it turned out, Pratt needed less than a minute to convince Gunn he was right for the part.

“I knew within 20 seconds of his audition this is absolutely the guy,” Gunn said. “And the truth is, Chris Pratt is the biggest movie star in the world. It’s just people don’t know it yet.”

Pratt has starred in other movies, including “Zero Dark Thirty,” “The Five-Year Engagement” and “Her.” But in the past year, he has risen to leading man status – his first being in “Guardians.”

But before he started shooting “Guardians,” all agreed Pratt needed to tone up a bit.

“They would send someone over to my house to measure me every week,” Pratt said. “It was like I was on ‘The Biggest Loser’ but there was no camera crew.”

“They would send me prop guns... I would take a picture with it, pose with the gun so they could see how it looked in my hand. Meanwhile, what they're secretly doing is, ‘How fat is Chris, still?’ And that's what the photo was,” he continued. “They're like, ‘Oh, we also need you to try on these gloves. Make sure it's a full body shot with the glove on.’ Oh, yeah, thanks.”

But as “Guardians of the Galaxy” rides its positive review into theaters Aug. 1, no one has more reasons to feel good than its unlikely star.

“I used to be a door-to-door salesman. I lived in a van,” Pratt said. “I’m a f------ Hollywood movie star now. I’m going to be happy every day that I walk onto set because I’ve got nothing to complain about.”