It ain't easy being the scariest gal on TV. When Ali Larter has a day off from NBC's Heroes (Mondays at 9 pm/ET), in which she plays dual personalities Niki and Jessica, she isn't kicking back. She's studying martial arts and taking striptease classes. Larter needs to master the "Kill Bill" stuff now that Jessica is an assassin for the shadowy Vegas mob boss Linderman. And the stripping? That's for a secret Heroes twist to be revealed later this season.
"The blessing and curse of being on Heroes is that you never know what they'll throw at you," says Larter, 31. "You have to be ready. Luckily for me I'm a kick-ass kinda gal. I'm also a bit schizophrenic — I need to change and reinvent myself a lot."

She came to the right show. When Heroes debuted last fall, we were first introduced to Niki, a sweet, luckless mom who supported her child by working in Internet porn. It was soon evident that Niki was being haunted by an alter ego, a murderous !@#% with Hulk-like strength named Jessica. Later, in a shock Larter says she didn't see coming, it was revealed that Jessica was Niki's dead sister, who was strangled by their alcoholic father. The gig is crazily complex, with Larter giving a performance both frightening and heart-wrenching.

"Ali's willingness to be so raw and emotionally naked on camera blows me away," says Heroes creator Tim Kring. Costar Sendhil Ramamurthy (Mohinder) adds, "She lets herself be vulnerable in a way most beautiful women on TV won't. She doesn't want to be the glamour-puss."

Actually, she tried that, and it didn't work. Born in Cherry Hill, New Jersey., Larter says she "grew up wanting to be a news broadcaster." Instead, she ended up in Hollywood in a string of babe roles. She was the cheerleader in the whipped-cream bikini in Varsity Blues, and was stalked by Death in the first two Final Destination flicks. Then, at 26, Larter fled show business and retreated to the East Coast for three years.

"I was too young and impressionable to handle the pressures of L.A." she recalls. "I needed to sit on park benches and figure out what kind of per­son I wanted to be." It seems something heavy drove her to this, but Larter declines to give spe­cifics, simply saying, "I'm a woman now. I am no longer the little girl who could be easily influ­enced." And is that woman spoken for? "Oh, I'm madly in love and he's mine, all mine," she admits with a giggle. "But I don't share secrets."

She will share a tasty tidbit about Heroes, however. The battle for control between Niki and Jessica leads to "a merging of the two," she says. "And we have an episode coming up that's set in the future. There is defi­nitely a winner then." Frankly, she's not wild about that. "I'll be sad when only one takes over," Larter says. "I'm having too much fun the way things are!"