Age: 41
Occupation: Representative from Wisconsin
Previous TIME 100 appearances: 0
He's become one of the GOP's brightest stars by embracing ideas that tend to kill political careers. Ryan's "Roadmap for America's Future" advocated sweeping entitlement reforms, from partially privatizing Social Security to replacing Medicare with private-insurance vouchers, though he hasn't veered from his party's antitax orthodoxy. Now, as House Budget Committee chairman, the wonky Wisconsinite is tasked with issuing his party's prescription for fixing the busted U.S. balance sheet, which even Republican colleagues think voters could find hard to swallow.