Sen left in 2003 after failing to secure the CEO job at the warehouse retailer, but she returned to BJ's in 2007 and was named CEO two years later. Last fiscal year she drove revenue to about $11 billion. In June two private equity firms agreed to buy BJ's for $2.8 billion.
Boardroom battles and power plays shaped this year's U.S. list, which boasts eight new faces and -- surprise! -- a new No. 1.
