Mark Zuckerberg

He can officially change his surname to Zuckerbucks. Mark Zuckerberg has kept firm control over Facebook ever since he created it in 2004, and he's long been fabulously wealthy as a result. The armchair critics were astounded when in 2006 Zuckerberg, then just 22, turned down a $1 billion offer from Yahoo's former CEO Terry Semel. That was nothing. A year later, he said no to Microsoft's Steve Ballmer, who offered $15 billion.

Zuckerberg is selling 533.8 million shares into the offering that goes public tomorrow, netting him more than $1.1 billion. But his $18.4 percent stake will, at the offering price, be worth a cool $19 billion.