William Kane Reilly (born January 26, 1940, in Decatur, Illinois) is an American conservationist and environmental leader with a distinguished career spanning government, non-governmental organizations, and the private sector. He served as Administrator of the U.S. Environmental Protection Agency from 1989 to 1993 under President George H.W. Bush, where he advanced market-based environmental policies, led the passage of the Clean Air Act Amendments, and headed the U.S. delegation to the 1992 United Nations Conference on Environment and Development in Rio de Janeiro. An environmental policy expert, his career includes educational achievements (BA from Yale, JD from Harvard Law, MS from Columbia), military service as a U.S. Army Captain, leadership roles as president of The Conservation Foundation and World Wildlife Fund, and post-EPA work as a Senior Advisor to TPG Capital and founder of Aqua International Partners. He has held numerous advisory and board positions, including co-chairing the 2010 National Commission on the BP Deepwater Horizon Oil Spill, and continues to advocate for climate action while working on his memoirs.