Olivia Thirlby Calls Mary-Kate "Chill" and "Normal"

Ellen Page better watch out! Mary-Kate Olsen is out for her best friend, or celluloid best friend at least.

Olivia Thirlby, who played Leah to Ellen's Juno in the dramedy of the same name, shares the screen with Mary-Kate in the upcoming The Wackness and cannot say enough good things about her other 21-year-old superstar colleague.

"She is probably the most chill, relaxed, normal girl I've ever met," Olivia tells OK! at the Snow Angels screening. "She doesn't wear her tremendous fame on her sleeve at all."

And despite having been in the public eye since infancy, Olivia, 21, says the younger Olsen twin could not be more down to earth.

"Meeting her, you would have no idea of her stature in the tabloid world," she says. "She's a really awesome girl."

Equally as grounded is Ellen, who's fresh off of an Oscar nomination for Best Actress for her turn in Juno, Olivia says.

"She's a really level-headed person. She's got her head screwed on tight."