Why Paul Rudd Decided to Play 'Ant-Man'

Funnyman starred in and helped co-write the script for the new Marvel movie.

But Rudd thinks that’s exactly what filmmakers were going for.

“Marvel seems to have this history of casting people and putting people in films that you would not necessarily associate with that kind of thing,” Rudd told “Nightline.” “I think that was part of the appeal for them, that I had never done anything like this. It was certainly part of the draw for me.”

In fact, Rudd helped co-write the script, adding his trademark sense of humor and giving this adventure film a comedic twist.

“I mean, it is funny,” he said, laughing. “Look, I'm riding around on an ant.”

Unlike Marvel’s other larger-than-life action heroes, such as Wolverine or The Incredible Hulk, Rudd’s character, Scott Lang, is a tiny superhero who can shrink down to the size on an ant with superhuman strength and on a mission to save the world.

“Most people aren't familiar with Ant-Man, first of all,” Rudd said. “But then when you tell people, ‘Well, he shrinks to the size of an ant,’ basically that means you're invisible.”

To play Ant-Man, Rudd has to strip down a little in the movie to suit up, which he said was “a great motivator” for getting in shape.

“I certainly exercised and trained. ... Little carbs. No cookies. No alcohol,” he said. ““My suit was real. ... I am a little biased, but I think it's the best-looking suit.”

Douglas plays Hank Pym, Scott Lang’s mentor and the mastermind behind the Ant-Man suit. It’s his first superhero movie.

“Ant-Man,” which opens in theaters nationwide Friday, is expected to maintain Marvel’s streak of No. 1 opening weekends. And after this, both Douglas and Rudd joked they have a new found appreciation for ants.

“I have a total, total respect for ants,” Rudd said. “I would never flick them. I don't smush them. I don't set ant traps. I let them alone. They're my brothers and sisters.”