Zuckerberg gets most of the credit for Facebook, but he was part of a launch team of four. None of Facebook's other co-founders are still at the company.
Dustin Moskovitz (pictured above) left the company five years ago to start Asana, a Web tool for team collaboration. Chris Hughes went the political route, joining the Obama campaign in 2008 as its director of online organizing. He recently used some of his Facebook wealth to buy The New Republic. Eduardo Saverin, Facebook's original financer, was pushed out of the company in 2005. He later moved to Singapore -- and gained notoriety for renouncing his U.S. citizenship.
NEXT: The Facebook employees