In the high-action TV show Nikita, Maggie Q plays the title character, a coolheaded rogue assassin being hunted by secret agents. She's also been a bomb-detonating operative with Tom Cruise in Mission: Impossible III and a gun-wielding killer opposite Bruce Willis in Live Free or Die Hard. In real life, though, she wouldn't harm a fly—or any other living thing. She's an ambassador for WildAid, a nonprofit whose slogan is "When the buying stops, the killing can too." A conservation activist for the past 14 of her 33 years, Q cares especially about sharks.

Q: WHY SHARKS?

A: They're a huge part of the ocean ecosystem. If we don't protect our oceans, if we don't allow fish to repopulate, we're in bigger trouble than people realize. It's the biggest ecosystem on the planet, and it's not living and breathing like it should.

Q: DID GROWING UP IN HAWAII INFLUENCE YOUR LOVE OF THE SEA AND ITS ANIMALS?

A: Definitely. I got an up-front experience with the natural world, and that was one of the things that led me toward conservation. Then I grew up and went, "Wow, people aren't getting this."

Q: WHAT WAS IT LIKE TO SWIM WITH AN ENDANGERED WHALE SHARK?

A: I thought there would be fear, but their energy was amazing, and they so honorably allowed me to enter their space. These things are enormous, like dinosaurs. And I was in their home. But they gently maneuvered around me and allowed me up in their face. I had an enormous sense of gratitude. I kept apologizing and thanking them, saying, "I'm so sorry, but this is all for you."

Q: WHAT WOULD YOU LIKE TO SEE HAPPEN IN REGARD TO SHARKS?

A: Now that I'm working in Toronto, I'd love to see shark fin get banned in Canada. If Canada does it, maybe the U.S. will.