Duncan William Clark (1910 – 5 August 2007) was born in New York City. He attended Fordham University and the Long Island College of Medicine, where he later became dean before joining SUNY Downstate in 1951.

In the 1960s Dr. Clark cited studies in other cities to effectively argue for adding fluoride to New York City's drinking water. In 1967 he co-wrote a well-known medical textbook, Preventive Medicine. He also studied other public-health issues, including hand washing among doctors.