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Jessica Chastain, Zero Dark Thirty
Role: Maya, the hyperfocused CIA agent who spends a decade tracking down Osama bin Laden.
Oscar History: Chastain earned a Best Supporting Actress nomination last year for The Help.
A Near Miss: Chastain almost turned down the role — without knowing a thing about it. When the filmmakers contacted her agent, they were told she wasn't available. Then Chastain's pal Megan Ellison, who financed Zero Dark Thirty, reached out. That led to a conversation with director Kathryn Bigelow, and the actress was so taken with the script she decided to free up her schedule. ''They showed a lot of trust in casting me,'' says Chastain, ''because there was no process.''
Getting Her Props: Screenwriter Mark Boal based Maya on a real-life agent while omitting identifying details. To help fill in the blanks, Chastain asked the props department to create reminders of her character's personal life. ''There are little clues in the movie, things that I added in,'' she says. ''There's this child's drawing in her room in Pakistan. Screensavers. Postcards that I would have certain things written on from friends back home. I wanted it to seem like there was this other life beckoning me.''
Up Next: Chastain appears opposite James McAvoy in a pair of linked films, The Disappearance of Eleanor Rigby: Him and Her, due later this year. —Rob Brunner
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Jennifer Lawrence, Silver Linings Playbook
Role: Tiffany, a deeply weird young widow who refuses to apologize for her weirdness.
Oscar History: Nominated for Best Actress for 2010's Winter's Bone.
Outside the Comfort Zone: Lawrence says she didn't have a handle on Tiffany at first, which was what excited her about the role. ''She was just a character I 100 percent did not understand at all,'' says Lawrence. ''She's like, 'I'm messed up, I'm not like everybody else, I've got issues. Take it or leave it because I like myself.'''
Hoofing It: Lawrence and costar Bradley Cooper spent weeks with choreographer Mandy Moore to fine-tune the climactic ballroom dance routine in the film. ''None of that was improvised, absolutely not. I'm a terrible dancer, so I would never have been able to do any of that,'' says Lawrence. ''When it finally came together, that scene really was just as fun as it feels.''
Star-Crossed: After Silver Linings, Lawrence and Cooper immediately reteamed for the period romance Serena. ''The plan now is to maybe have a little box set,'' she says with a laugh. ''When we were shooting, we kept talking about other scripts we were doing and he'd be like, 'Well, that sounds great!' And I'd say, 'Yeah, but you can't play my dad after you've played my lover.'''
Up Next: In addition to Serena, due later this year, she stars in the Hunger Games sequel Catching Fire (Nov. 22). —Karen Valby
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Emmanuelle Riva, Amour
Role: Anne, a proud former piano instructor dwindling into dotage and dependency under the care of her husband, Georges (Jean-Louis Trintignant).
Oscar History: With her first nomination, Riva becomes the oldest Best Actress contender in Academy history.
Amour at First Sight: Though both Riva and Trintignant have worked in the French film industry for more than half a century — and each starred in one of the films in Krzysztof Kieslowski's famed Three Colors trilogy — the two actors had never worked together before Amour. But Riva knew immediately that the casting would work perfectly. ''When I read the script knowing Jean-Louis would be Georges,'' she says, ''I believed in the couple. I could see us in my head. And so when we started working, we didn't have to have known each other in order to immediately have that intimacy.''
Then and Now: Riva is probably best known for her role in Hiroshima Mon Amour, Alain Resnais' 1959 cinematic tone poem about love and loss among the ruins of post-WWII Japan, and the actress sees parallels between the films on opposite ends of her storied career. ''On one side there's Hiroshima, a film about impossible love,'' Riva says. ''And on the other side, in the final stage of my life, there's a film about a love that's possible until death. It's a wonderful balance.''
Up Next: The actress has yet to announce her next project. —Keith Staskiewicz
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Quvenzhané Wallis, Beasts of the Southern Wild
Role: Hushpuppy, a clever bayou girl facing down an apocalyptic flood in a dreamlike fable.
Oscar History: With her first nomination, she becomes the youngest-ever Best Actress nominee, beating out Whale Rider's Keisha Castle-Hughes, who was 13 when nominated in 2004.
Name Game: It's intimidating to look at, but her first name is pronounced Kwah-VEN-jeh-nay. Asked recently whether the grown-ups she meets have a grasp on saying it right, she just laughed, saying, ''They're working on it.''
Early Discovery: Wallis was only 5 when her mother brought her to an open audition for the role near her hometown of Houma, La. Wallis recounted the experience at the Sundance Film Festival last year, standing beside director Benh Zeitlin. ''How I got found was from my mom and her friend. They knew about the library auditions,'' she said, pronouncing it lye-barry. ''So we went to the lye-barry, and he said I was the Hushpuppy girl,'' she concluded, pointing at Zeitlin. The filmmaker chose her out of about 3,500 kids. ''She's an incredibly wise and strong human being,'' Zeitlin said. ''When we're on set, I can talk to her like an adult and she'll talk to me like an adult. It's strange — she can sort of swap being a little kid and being the most sophisticated person you can imagine.''
Up Next: She returned to Sundance this month with the short film Boneshaker and has a role in director Steve McQueen's drama Twelve Years a Slave, due later this year. —Anthony Breznican
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Naomi Watts, The Impossible
Role: Maria Belón, a mother of three vacationing with her family in Thailand when the 2004 tsunami strikes.
Oscar History: She was nominated for Best Actress for 2003's 21 Grams.
No Words Necessary: Watts was a little anxious about meeting the real-life Maria, who was severely injured in the natural disaster and separated from her husband and two of her three young sons. ''I was so nervous,'' the British-born actress recalls. ''How do you ask all these ridiculous questions that an actor wants to know? It feels wrong and perverse.'' The two women, who went on to become close, at first just sat and stared quietly at each other. ''She just welled up, and I welled up,'' Watts says. ''It was like the story was told without words. It was all there in her eyes.''
Waterworks: Shooting scenes involving the deadly tsunami itself required the actors to film in water for nearly a month. ''I just got the s--- beaten out of me,'' says Watts. ''I knew it wouldn't be fun because working with water is always difficult. That's its reputation and it lived up to it.'' The extra strain paid off on screen, though. ''If we had been on the greenscreen flailing around,'' she says, ''it wouldn't have been the same performance.''
Up Next: Watts plays the title role in a just-wrapped Princess Diana biopic, Diana (due later this year). —Sara Vilkomerson