John H. Gagnon (November 22, 1931 – February 11, 2016) was a pioneering sociologist of human sexuality who wrote and edited 15 books and over 100 articles. His key work is Sexual Conduct: The Social Sources of Human Sexuality (1973), which he co-authored with William Simon. He was Distinguished Emeritus Professor of Sociology at the State University of New York at Stony Brook where he taught and researched from 1968 to 1998.