Zoë Saldana's first words are a health warning. "You shouldn't use that," she says, nodding at the Splenda. "Use brown sugar." The lithe 31-year-old actress is sitting in Hugo's, an organic café in West Hollywood, wearing a fitted gray sweater dress over black leggings, nursing a cup of pomegranate white tea (unsweetened, naturally), and musing about the dangers of artificial sweeteners. You might not expect this sort of talk from an outer-borough New York girl, raised in Queens by way of the Dominican Republic. But Saldana has mined a strange blend of erudite grace (she's a classically trained dancer) and raw sensuality to become the reigning queen of sci-fi blockbusters—last summer as Lieutenant Uhura in J.J. Abrams' reboot of Star Trek and now in this month's hotly anticipated Avatar.

"I've become a little action whore," Saldana says. Emphasis on action, not the other thing. "I've always gravitated toward the Sigourney Weavers, the fucking Linda Hamiltons, the Angelina Jolies. I just love strong women that are in tune with their bodies—that don't just use their bodies as sex tools. I'm very dominant—feisty. I'm not a man-hater, just a very proud woman."

In fact, Saldana has yet another action movie in the works; she's just back from Puerto Rico, where she's been shooting an adaptation of The Losers, a wham-bam graphic novel. She can't seem to help moving her hands and upper body—fluidly, expressively—as she speaks. There's little doubt her physical abilities helped her snag a starring role in Avatar, which is being directed by James Cameron, creator of the Terminator franchise and Titanic. It's taken more than $200 million and 15 years for Cameron to make this CGI fantasy film—he had to wait for the 3-D technology required to produce his vision to be invented—which suggests the decision to cast Saldana opposite Sam Worthington wasn't made lightly.

"I'm such a physical person, action-film work came natural," Saldana says. "Even at 5 years old, I was watching Sarah Connor. If you fucking switched the channel to The Last Unicorn, I would've been like, 'Ah, Jesus—just find your way home, you fucking unicorn!'"

Saldana was one of three sisters raised by a single mother in Queens. After her father passed away when she was 9, Saldana spent seven years studying ballet in the Dominican Republic. She returned to New York for her last two years of high school, immersed herself in after-school theater programs, and eventually made her big-screen debut in the 2000 ballet flick Centerstage. She followed that with small roles in Pirates of the Caribbean and Steven Spielberg's The Terminal (in a bit of cinematic foreshadowing, she played a Trekkie). But the fact is, nothing she did prior to taking her seat on the bridge of the Starship Enterprise suggested that she had the kind of unbridled attitude to quicken pulses—human, Vulcan, and sci-fi geek alike.

"Zoë's definitely fiery," says Abrams, who has already signed her for the Star Trek sequel. "She has the fortitude for you to put her in control. She could really do the job—not just look good in a ridiculously short dress."

Good thing, because, technically, Saldana's body isn't even in Avatar; Cameron used motion-capture technology to transform her into Neytiri, a blue, 10-foot-tall kung-fu-fighting creature. But she didn't just read lines in a sound booth. "Motion capture isn't like shooting ," Saldana explains. "You're in a suit with all these dots on you, and whatever you do, they get it. Sam and I did all sorts of stupid shit. If you burp, your character burps. I'd shake my booty, and you'd see my character shaking her booty."