Who are the African American chairmen and lead directors of corporate boards? As part of our development of the exclusive BLACK ENTERPRISE Exclusive Registry of African Americans on Corporate Boards---our listing of black board members from the 250 largest companies on the S&P 500---we now reveal African American corporate governance leaders who are responsible for charging CEOs and senior management to promote greater transparency and accountability within corporations. These individuals exhibit qualities that set the tone for the complex deliberations---ranging from acquisitions and divestitures to executive compensation and layoffs---held in the boardroom that impact shareholder value. RELATED: We Must Put An End to 'Male, Pale & Stale' on Corporate Boards According to a PricewaterhouseCoopers study, lead directors not only improve board performance by facilitating board discussions and helping directors reach consensus, but also have the authority to preside over executive sessions and help deal with difficult or underperforming directors as well. So, while expanding African American board representation will help drive the advancement of African Americans in the corporate space, those in leadership positions have a unique responsibility to facilitate this change. Now, discover who the leaders of the board are among the nation's largest publicly traded companies on the next pages ... Leslie Brun, Non-Executive Chairman, Automatic Data Processing With more than 30 years of investment banking, commercial banking, and financial advisory experience, Brun serves as chairman and CEO of Sarr Group, L.L.C., a diversified holding company. Brun previously served as managing director and head of investor relations in the New York office of CCMP Capital Advisors. Ursula Burns, Chairman, Xerox Corp. Burns, who also serves as the company's CEO, leads more than 14,000 employees who serve clients in more than 180 countries. Under her leadership, the company's sales are approaching $23 billion, and Xerox stands as the world's leading enterprise for business process and document management. Kenneth Chenault, Chairman, American Express Co. After joining American Express in 1981, Chenault climbed the ranks to become chairman and CEO of the company in 2001, making him one of the first African Americans to hold this position at a major publicly traded company. Kenneth C. Frazier, Chairman, Merck & Co. Inc. After serving in a number of leadership roles at the company, Frazier became chairman and CEO of the global healthcare giant in 2011. Our 2014 BLACK ENTERPRISE Corporate Executive of the Year, Frazier is currently focused on creating sustainable value through considerable investments in talent, research, and innovation. John Thompson, Independent Chairman, Microsoft Thompson, an active investor in early-stage technology companies, is the current CEO of privately held Virtual Instruments, whose products are designed to ensure the performance and availability of applications deployed in virtualized and private cloud computing environments. Thompson joined Microsoft's board in 2012 and became independent chairman in 2014. Reuben Anderson, Lead Director, AT&T A former Mississippi judge, Anderson has served as senior partner in the law firm of Phelps Dunbar, LLP since 1991, where he practices in the areas of commercial and tort litigation and regulatory and governance matters. Anderson has served on the AT&T board since 2006. Virgis W. Colbert, Lead Independent Director, Lorillard Inc. Having served a number of key leadership roles at Miller Brewing Co. since 1979, such as executive vice president of Worldwide Operations from 1997 to 2005, Colbert currently serves as a senior advisor for MillerCoors L.L.C. Colbert became a director of Lorillard in 2008 and has served as lead director since 2013. Earl Graves Jr., Lead Director, AutoZone Inc. Graves has served as the president and CEO of BLACK ENTERPRISE since January 2006, and as president and chief operating officer from 1998 to 2006. He has served as lead director of AutoZone since 2009. Alexis M. Herman, Lead Director, Cummins Inc. Herman, the 23rd U.S. Secretary of Labor under President Clinton, currently serves as chair and CEO of New Ventures L.L.C., a corporate consulting company, since 2001. Adebayo Ogunlesi, Lead Director, Goldman Sachs With more than 20 years of experience in the financial services industry with companies such as Credit Suisse, Ogunlesi currently serves as chairman and managing partner of Global Infrastructure Partners, an independent infrastructure fund manager. He has served as a director for Goldman Sachs since 2012.