AGE 41: Sergey Brin

Co-founder of Google

What makes him powerful: Brin is one of the geniuses behind Google. He's responsible for trying to decide which ideas Google will pursue, overseeing Google X's "moon shots," and the hush-hush long-term projects that try to tackle big problems — think Google Glass, driverless cars, smart contacts for diabetics, and flying wind turbines that generate power.