Mark Zuckerberg

Founder and CEO
Facebook

Zuckerberg leads Facebook, which he founded in 2004. As such, Zuckerberg is responsible for setting the overall direction and product strategy for the company, leading the design of Facebook's service and development of its core technology and infrastructure. It's worked out well so far for the young entrepreneur. After founding the social networking site as an undergraduate at Harvard University, where he studied computer science before moving the company to Silicon Valley, he has seen it grow to 500 million users worldwide and a private-market valuation of $25 billion. We'll admit it: We're impressed.