40 Under 40

They're the hottest young stars in business across the globe. They're innovators, disrupters, and job creators; in fact, it's a pretty safe bet you're going to be working for them someday -- if you aren't already! They're in technology, yes, but also in movies, music, athletic wear, and even curry-flavored chocolate. And the scary thing is they're just getting started.

1. Mark Zuckerberg
Mark Zuckerberg
Founder and CEO, Facebook
Age: 27
Industry: Technology

This may have been the year your grandmother joined Facebook. The Harvard dropout and tech wizard is a household name, thanks in part to The Social Network, but the real-life script is still being written. In 2011 his baby hit 800 million users and was valued at $50 billion, setting the stage for a monster IPO to come. The company also partnered with Skype and redesigned key parts of its service, leading to the usual temporary backlash.

On the hunt: Zuck made headlines earlier this year when he told Fortune his goal for 2011 was to eat only animals he had personally killed.

Editorial package reported by Katie Benner, Scott Cendrowski, Betsy Feldman, Mina Kimes, Alex Konrad, Beth Kowitt, Colleen Leahey, Michal Lev-Ram, Tara Moore, Tory Newmyer, Daniel Roberts, Christopher Tkaczyk, Anne VanderMey - Last updated October 25 2011: 5:11 PM ET