President and CEO, Sam's Club
2011 rank: 23
Brewer, who began as a scientist at Kimberly-Clark, became CEO of Wal-Mart's warehouse club (fiscal 2012 revenue: $54 billion) in February after a stint as head of Wal-Mart's eastern
division. It is a big promotion: She heads one of only three operating segments, and she reports directly to CEO Mike Duke.