LOS ANGELES — For more than a decade, Paul Rudd has served as a comedic chameleon, effortlessly moving from sidekick (“Anchorman: The Legend of Ron Burgundy,” “The 40-Year-Old Virgin”) to scene stealer (“Knocked Up,” “Forgetting Sarah Marshall”) to straight man (“Dinner for Schmucks,” “I Love You, Man”). He’s tackling his most transformative role yet in “Our Idiot Brother.”

The affable 42-year-old actor grew his hair and beard out last summer to portray Ned, an easygoing organic farmer whose lack of ambition and independence continually frustrate his family. Rudd developed the earnest character with friend-neighbor-director Jesse Peretz. (The pair first worked together on the 2002 improvisational comedy “The Chateau.”)

The indie dramedy, which was snapped up by The Weinstein Co. at the Sundance Film Festival earlier this year, is distinctly different from any of the other movies listed on Rudd’s seemingly never-ending resume. It’s not as silly as “Role Models” or “Dinner for Schmucks” nor is it as serious as “The Cider House Rules” or “The Shape of Things.”

“It’s just like life,” Rudd recently said over breakfast. “It’s not unrealistic or a cliche. That’s one of the things I really liked about this project. There’s a definitive point of view. To me, the character wasn’t just about his look: the long hair, the beard, the Crocs. Those are external things. He’s just a good guy who’s into bio-dynamic farming.”