Age: 30 and 28 (estimate)
What he's done: Graves grew Uber from a one person company to a $17 billion company with the aid of cofounders Travis Kalanick, Oscar Salazar and Garrett Camp. Graves was the company's first CEO. Now he's the company's board director and head of global operations.
Geidt was Uber employee #4. She now heads up global expansion for the company, which operates in 45 countries.