The Top 25 Managers -- The Best Regulators
Joel Klein, Former Assistant Attorney General
Klein, 54, who resigned his post in October, put the bite back in antitrust enforcement. He won more than $1 billion in fines and settlements. He sued AMR's American Airlines (AMR), halted MCI WorldCom's (WCOM) merger with Sprint (FON), and, of course, won a court order to break up Microsoft (MSFT).