Chief Operating Officer, Facebook
Sandberg remains one of Fortune's Most Powerful Women for good reason. As Mark Zuckerberg's right-hand since 2008, the former Google exec has been instrumental in transforming Facebook into a viable business, one largely driven by advertising. Sandberg reportedly recused herself from selecting underwriters due in part to a personal friendship with Michael Grimes of Morgan Stanley. It's that decision some argue may have been to Facebook's detriment.