William H. Schlesinger (born April 30, 1950) is a biogeochemist and the retired president of the Cary Institute of Ecosystem Studies, an independent not-for-profit environmental research organization in Millbrook, New York. He assumed that position after 27 years on the faculty of Duke University, where he served as the Dean of the Nicholas School of the Environment and Earth Sciences and James B. Duke Professor of Biogeochemistry.