William G. Parrett is the former chief executive officer of Deloitte Touche Tohmatsu and a DTT senior partner. In a career spanning nearly four decades, he has served many large national and multinational businesses. He co-founded the Deloitte Global Financial Services Industry practice and served as its first chairman.

Parrett is a member of the International Business Council of the World Economic Forum, and the Transatlantic Business Dialogue (TABD). He is an executive member of the International Chamber of Commerce and serves as chairman for the United States Council for International Business (USCIB) and an international councilor for the Center for Strategic & International Studies (CSIS). 

A long-time advocate of community service, Parrett is a member of the Committee to Encourage Corporate Philanthropy (CECP), and the G100 Group.