NICOLE KIDMAN

The star of both Margot At The Wedding and The Golden Compass tells Mike Goodridge how she tackled such dark roles.

We may see her on red carpets looking every inch the style queen, but Nicole Kidman says her natural instincts are not to embrace the glamour. "I seek out characters like Margot," she says, referring to her latest bold performance in Noah Baumbach's unforgiving portrait of family life, Margot At The Wedding. Margot is a successful writer whose stuck-up manner and critical nature has had many brand her the most unlikeable character on screen this year.

"I'm protective of Margot," Kidman tells Screen on the phone during a break from shooting Baz Luhrmann's romantic epic Australia. "She's got a sting, she's prickly at times, but she's breaking. If there's a sound you're hearing, it's fingers down a chalkboard. She's at that time in her life where she's thinking, 'What have I spent the last 45 years - and I think she is about 45 - doing''

"Instead of finding peace at that age, she's finding distress," continues Kidman. "She's unable to express the way she feels. I've got to put voices to these women who aren't the most beautiful in their nature. That's mirroring human life."

Kidman says the script by Baumbach was shot word for word and that the actors did not improvise at all. "Maybe people feel Noah has misanthropic tendencies," she says, "but he's showing people in struggles and you're able to laugh and squirm at his films."

Many consider Margot a brave choice for Kidman, one of the world's biggest celebrities, but then again the actress has peppered her career with intriguing choices such as Dogville, Birth and Fur: An Imaginary Portrait Of Diane Arbus.

"I never think about taking roles in relation to who I am, to who Nicole is," she muses. "That would not be pure, artistically. I don't know whether that's my biggest strength or weakness."

Mrs Coulter, in Chris Weitz's film of Philip Pullman's The Golden Compass, is almost the antithesis of Margot. We first see her on screen slink seductively down the dining hall of an Oxford college in a full-length gold dress, and, as is the intention of that introduction, Kidman injects glamour, femininity and menace to the film.

"When they put you in a gold dress, I see what they're trying to do," she laughs. "Chris and the costume designer and Ileen (Maisel, the film's executive producer) kept on telling me to embrace the glamour of her and I agreed to put it in their hands.

"She's a really complicated character," continues Kidman. "She likes the attention but beyond that, she is empowered. She is really aware of her intelligence, so it's great to play a villain who is intelligent. Although I don't like to use the word villain. You feel her motivation in the things she does."

Kidman agreed to take the part when Pullman himself asked her to consider it. "He wrote me a really lovely letter telling me why he wanted me to play it," she recalls. "When an author does that, it has such weight."

And should New Line produce the second two films in the trilogy, Kidman is committed, both contractually and emotionally. "I can't wait," she says. "The character gets amazing in the second and third ones."

Next up for the actress is a supporting role in Stephen Daldry's The Reader, which is set to shoot in Germany in February. First, she has another four weeks to go on Australia, which has already been shooting for nine months. "Unlike Margot, my character in Australia is the warmest, yummiest person to play. It's an easier place to exist in."

Kidman, who has been in the make-up chair for the duration of the interview, says she has to go back to set. "I have to run off and brand a cow."

MARION COTILLARD

The French actress talks to Peter Bowen about capturing the essence of Edith Piaf.

In early 2005, a year before she was cast, Marion Cotillard learned that writer-director Olivier Dahan was writing Edith Piaf biopic La Vie En Rose with her in mind. She had no idea why - she was, for example, much taller than the 4'8" Piaf. But later she overheard Dahan explain he had seen something in her eyes.

If the eyes are the window to the soul, Cotillard sought to capture that with Piaf. At the start, the 32-year-old Cotillard knew very little about France's most famous chanteuse: "I knew she always dressed in black on stage, and she had a specific body language with her hands - black dress, tiny woman, strong voice." To find the person behind the legend, Cotillard immersed herself in her life, reading biographies, listening to her albums, watching the Super-8 films by Piaf's accordionist. "I thought that by watching and listening to her without imitating her, I would learn about her. I never tried to do what she did. My aim was to understand her - her heart, her soul."

As such, Cotillard saturated herself in Piaf, and waited to see what would ignite: "I never rehearsed. The first time I heard that voice or I moved like her was on the set."

The hardest challenge for Cotillard in this method was accepting all the different aspects of Piaf. Cotillard tells how, when she embarked on a journey to understand the singer's dark side, "it took me inside her childhood. I understood when you are abandoned as a child, then you will search for love all your life. That's why Piaf was terrified of being alone; and why she was a tyrant at times."