It was dusk on the Sunset Strip here when Noomi Rapace swooped into an oak-paneled bar, looking nothing like herself. Swathed in crepe the color of orange sherbet, her skin luscious, her hair tousled, she could have been any starlet making the rounds. But she might have been Someone. Eavesdroppers craned their necks, not quite sure.

Then, a murmur of recognition from a banquette just beyond. “It’s her,” a man whispered furiously to his companions. “The Girl With the Dragon Tattoo!” These days Rooney Mara’s pale, pierced visage looms on billboards for David Fincher’s take on the Stieg Larsson novel, the first of the Millennium trilogy best sellers. But for fans of the original Swedish films, Ms. Rapace (pronounced Ra-PAHSS) will forever embody Lisbeth Salander, Larsson’s avenging angel: razor sharp and tough as tungsten, a tiny freak of nature able to bring a man twice her size to his knees. That might have been her face up on the billboards. But Ms. Rapace didn’t even consider auditioning; she wasn’t interested in dwelling on a character that had consumed her for a year and a half, transforming her from a well-regarded Swedish actress into an international sensation. “I was done with her,” Ms. Rapace, 31, said, sipping peppermint tea at the Sunset Tower Hotel and looking remarkably normal for someone specializing in the psychically ravaged. On the last day of shooting the trilogy’s concluding film, “The Girl Who Kicked the Hornet’s Nest,” when producers arrived with Champagne, Ms. Rapace ran to the bathroom and vomited. “I was throwing up for 45 minutes,” she said. “I couldn’t stand. It was so clearly my body throwing Lisbeth out.” ” ‘God, get out!,’ ” she suddenly shouted, laughing raucously as she recalled the spontaneous exorcism. On Friday, five days ahead of the release of Mr. Fincher’s film, Ms. Rapace will make her English-language debut alongside Robert Downey Jr. and Jude Law in “Sherlock Holmes: A Game of Shadows,” directed by Guy Ritchie. As Sim, a Gypsy fortuneteller, the chameleonic Ms. Rapace assumes a less brazen disguise — a flowing mane, kaleidoscopic petticoats and knife-throwing skills — in a commercial calling card.

“I thought she felt fresh and strong and different,” Mr. Ritchie said of Ms. Rapace. “She’s creative. She has ideas, some good and some not so good. She’s full of energy and aggressive, and born to be an actress, really. Given her own way, she was fully enthusiastic about stabbing as many people as she could, so I had to quell her passion a bit.” The role fits with Ms. Rapace’s image of herself as a citizen of the world. “I never felt like a typical Swedish girl,” she said. “I always felt like I was on the move, that I was going towards something.” Most recently Ms. Rapace has pointed her compass at the United States, which she described as a country of possibilities where nothing is too big or too complicated, at least not in the film industry. At least not for her. In June she will star as a scientist with a deep faith in God in Ridley Scott’s “Prometheus,” his fiercely guarded science-fiction offshoot of “Alien” for which he cast her from their first meeting. “I didn’t tell her but decided she would be the female lead in ‘Prometheus,’ ” he wrote in an e-mail. “My first impression was how different she was from the person in ‘Dragon.’ I realized here was a great actress. The real thing.” Directing her, he added, was one of the best experiences he has had.

“It’s my first big American movie in which she’s the heart,” Ms. Rapace said of her character, Elizabeth Shaw. “She’s the one you follow to the end.” Ms. Rapace’s unwillingness to shrink from physical torment — “In some scenes, I’m running around in underwear, doing things that are quite hard core,” she said of Elizabeth — might explain Hollywood’s eagerness to put out the welcome mat. That, and her gender-crossing appeal. “She’s definitely sexy and mysterious, which men like,” said Niels Arden Oplev, who directed her in “Dragon Tattoo.” “I think women identify with her because she’s a fighter, but she has a fragile side. She’s beautiful, but she’s not a threat.” Still, that beauty gave Mr. Oplev pause when he was casting “Dragon Tattoo” — an obstacle she seemed to intuit, arriving at her screen test channeling the punk she’d been at 14. “Noomi has something that’s very rare for an actor,” he said. “I call it the hand-grenade effect. She has this dark energy that comes from inside, and you know it’s going to blow up in your face. It’s a combination of high credibility and seductive unpredictability.” A daughter of the Swedish actress Nina Noren and a Spanish flamenco singer, Rogelio Durán, Ms. Rapace moved to Iceland at 4 with her mother and stepfather and by 7 had discovered her vocation after landing a nonspeaking role in a Viking saga. Two years later she was back in Sweden, memorably screaming in a school play about Moses, “My baby is gone!”

“And everybody is like, ‘What’s wrong with her?’ ” she said. “This 9-year-old, holding onto this doll. I think I’ve always been doing everything 100 percent.” At 15, while drinking her way through adolescence, she moved on her own to Stockholm to study drama. The next year she landed a part in a soap opera and three years after that her first real film role. (These days she divides her time among Los Angeles, London and Stockholm.) “I left home early, I married early, I had a child early,” Ms. Rapace said, referring to her ex-husband, the actor Ola Rapace, who is filming the James Bond film “Skyfall,” and their 8-year-old son, Lev. (Their adopted surname means “bird of prey” in French.) “Had anyone tried to hold me back, it would have been impossible.” She indulged her obsession with testing boundaries in films like Simon Staho’s “Daisy Diamond,” trimming her pubic hair on screen in her role as an actress who breaks under the pressure of single motherhood, which earned her a Bodil Award from the National Association of Film Critics in Denmark. In Pernilla August’s “Beyond” Ms. Rapace teeters on the brink as the adult child of alcoholics. The drama is Sweden’s current entry for the foreign-language Oscar. “The Girl With the Dragon Tattoo” and its no-less-graphic sequels, “The Girl Who Played With Fire” and “The Girl Who Kicked the Hornet’s Nest” (both directed by Daniel Alfredson), brought her other honors, including the Guldbagge Award from the Swedish Film Institute. “With her hard gaze and underlying menace, Ms. Rapace — with Salander as her guide — holds your attention in these mostly unmemorable movies,” Manohla Dargis wrote in The New York Times. “Particularly crucial is her punishingly physical performance, which underscores that this is very much a story about what some men do to women’s bodies.” Don’t blame the men, Ms. Rapace countered: “Sometimes people say to me, ‘All those male directors who want you to do those sexual things.’ And I say, ‘It’s always been me.’ It’s always been me that wanted to do it and go further out and try to see how to close to the edge can we go.” She added, “All my characters, even the most cracked, crazy, broken souls, are always something from me.” Mr. Oplev, who will direct Ms. Rapace and Colin Farrell in the thriller “Dead Man Down” next year, said that American audiences are craving that something — cracked, crazy or otherwise.

“I have a bet with Noomi that she’s going to be a major star, and we argue about it each time we meet,” he said. “I always say to her, ‘When are you going to have enough? When are you going to admit that I won?’ “