Mercer "Merce" Reynolds III (born 17 June 1945) is an American businessman. He was the finance chair of U.S. President George W. Bush's 2004 re-election campaign.

Reynolds, born in Chattanooga, Tennessee, earned a bachelor's degree in business administration from the University of North Carolina at Chapel Hill, and an M.B.A. from the University of Tennessee. After serving briefly in the United States Army (1968-1969), he worked for Coca-Cola for ten years.

In 1979, Reynolds and business partner William DeWitt founded the investment firm Reynolds, DeWitt & Co.; he was its co-chair until 2001. Reynolds' other business ventures included Spectrum 7, an oil company which he co-chaired from 1980 to 1985 and which, in 1984 merged with the struggling firm Arbusto Energy, which was owned by George W. Bush. Reynolds was later a investor with Bush in the Texas Rangers baseball team. From 1985 to 2001, he was CEO of Reynolds Planataion, a golf community near Lake Oconee in Georgia.

Reynolds was Ohio finance chairman for George W. Bush's 2000 presidential and campaign, raising over $600,000 and was named to co-chair Bush's inaugural committee. From August 2001 to September 2003, Reynolds served as U.S. ambassador to Switzerland and Liechtenstein. As the national finance chair of U.S. President George W. Bush's 2004 re-election campaign, Renyolds helped raise over $200 million for the successful effort and is sometimes credited with helping to deliver Ohio's key electoral votes to the president. He has been a frequest guest of the president at the White House and at Camp David, and was a leading contender for the post of Commerce Secretary upon the 2004 resignation of Don Evans.

Reynolds has been active in fundraising for community and civic organizations as well, for Summerbridge, a tutoring program for inner-city youth in Cincinnati, for the National Coalition for the Protection of Children and Families, and for the United Way. In the feild of foreign policy, he sits on the advisory board of the Center for Strategic and International Studies and has been involved with the Bridging the Rift Foundation in the Middle East.

Reynolds and his wife, Gabrielle, live in Indian Hill, Ohio; they have five children. Gabrielle Reynolds was appointed by President Bush in 2004 to serve on the board of trustees of the Kennedy Center for the Performing Arts. Rumours in January 2005 linked him with the vacant position of US ambassador to the Court of St James (ie the United Kingdom).