She started off on Lost as a meek, Korean-speaking wife. Now she's a tough cookie—and fan favorite—who has shot a woman, revealed a steamy affair and turned up mysteriously pregnant, a puzzle that will be solved in April 25's episode. Kim, 33, a single Staten Island native ("I'm always on an island!"), became a movie star in South Korea in her 20s before taking on the castaway life.

• ON HER SEXIEST COSTAR
Stubbled Matthew Fox? Swaggering Josh Holloway? Her square-jawed screen hubby Daniel Dae Kim? Nah. "Terry O'Quinn [Locke] is the sexiest guy. You're just captivated by him."

• ON HER MOST PAIN-AVERSE COSTAR
She has slapped three castmates—but only Holloway insisted on faking it. "He had a photo shoot the next day and he didn't want to be swollen. I teased him, saying he wasn't a real man. He said, 'I don't care.'"

• THE BEST THING ABOUT THE JOB
"Working in Hawaii—it truly is a magical place. I feel at home."

• THE WORST THING ABOUT THE JOB
"Flying cockroaches. I swear, they are like birds. One flew into my condo. I called a security guard to help me."

• THE WEIRDEST THING ABOUT THE JOB
"When I go to Korea and I watch Lost, it's dubbed in Korean—someone else is speaking my lines."