39. Satya Nadella

Title: CEO, Microsoft

Country: US

Age: 48

Since becoming Microsoft's third CEO last year, Satya Nadella has been busy helping the technology company become relevant again. While Microsoft is still a software giant — it pulls in $95 billion in sales — it's far from its former glory as tech's innovative, undisputed leader.

But Nadella, a Microsoft veteran of 23 years, has made significant progress in rejuvenating the company: He successfully released Windows 10, a huge hit that attracted over 110 million users in three months; he converted Microsoft rivals like Salesforce and Oracle into partners; he launched Microsoft into the growing Internet of Things market with a new database, cloud service, and big-data analysis service; and he oversaw Microsoft's biggest layoff round ever while still maintaining his likability among employees.