Ryan Graves, 32
Graves was ride-sharing giant Uber’s first CEO, and was hired as the company’s first employee in 2010 after he responded to a recruiting tweet from cofounder and now-CEO Travis Kalanick in 2010 promising “BIG equity” in a yet-unknown startup (Graves’ response: “here’s a tip. email me. : )”). Graves—who was previously a management trainee at GE Healthcare and an unpaid intern at Foursquare—recruited the company’s first engineers and drivers; once the company took off in 2011, he became Kalanick’s number two, tasked with building teams and recruiting drivers in each city in the U.S. Now, with 2,300 employees reporting to him, Graves is focused on building teams in new growth areas like China and Southeast Asia. On the Uber board since its formation in 2010, his stake in the company is said to be worth close to $1 billion.