Change from last year: +$15 billion
Age: 30
Mark Zuckerberg founded Facebook in his Harvard dorm room in 2004.
Zuckerberg's net worth grew by $15 billion this year, the biggest gain of anyone on Forbes' list. In the last year, Zuckerberg led big acquisitions of startups WhatsApp and Oculus VR, and Facebook stock has soared.
He's also caused some controversy in his San Francisco neighborhood, where extensive construction work on his home has made parking difficult for his neighbors.
Source: Forbes