
Age: 54
P&G COO Bob MacDonald now has the inside track to succeed A.G. Lafley, but don't be surprised if Arnold, who started at P&G in 1980, goes on to run another Fortune 500 company. Recent appointments to the Disney and McDonald's boards burnish her résumé.
NEXT: Oprah Winfrey
Last updated October 16 2008: 10:16 AM ET