Co-founder and CEO, Polyvore
40 Under 40 rank: 32
When the Hong Kong native started her career at Google in 2004, her mentor, Marissa Mayer, taught her to "always take the more challenging path." Lee heeded that advice four years later when she decided to leave to join the fledgling fashion website Polyvore. Lee was uniquely qualified for the job, with her computer science background, love of fashion (she was already a Polyvore addict), and quirky creative side (she loves Japanese manga comic books and hopes to write a graphic novel). Lee moved into the CEO spot this year -- and the company added "cofounder" to her title -- but her eccentric side still comes through. While being photographed in Marin Headlands, Calif., she spontaneously chose to climb a tree. "Was that creepy?" she asked after she climbed down. "Whatever. I like creepy."
Who are 2012's young business stars? We've got the CEO of a blue-chip beer brand, an airline CEO who just placed the largest order in commercial aviation history, and Warren Buffett's new prodigy, among the Silicon Valley hotshots and others.