Anne M. Mulcahy

Having rescued Xerox, Mulcahy spent years preparing Ursula Burns to follow her, making her president in 2007 and giving her the operational lead well before the 2009 handover. It was the first time one woman succeeded another as chief executive of a large American company, but the more useful point is the method: a long, public apprenticeship, with Mulcahy staying on briefly as chairman before stepping away.