Nicknamed “don of the PayPal mafia,” the eccentric cofounder and former CEO of the online payment service, and former child chess prodigy, now serves as president of the $3 billion hedge fund Clarium Capital Management LLC. Thiel’s initial investment of $500,000 in the wildly popular social networking site Facebook is now worth over $1 billion. Bonus: He’s doing his part to keep us all around a little longer, having recently donated $3.5 million to the Methuselah Foundation, an antiaging research group.