Nicholas A. Christakis (US: NIK-ə-liss kriss-TAK-iss) (born May 7, 1962) is a Greek-American sociologist and physician known for his research on social networks and on the social, economic, biological, and evolutionary determinants of human welfare (including the behavior, health, and capabilities of individuals and groups). He is the Sterling Professor of Social and Natural Science at Yale University, where he directs the Human Nature Lab. He is also the co-director of the Yale Institute for Network Science. Christakis was elected a Fellow of the National Academy of Sciences in 2024. He was elected a Fellow of the National Academy of Medicine in 2006; of the American Association for the Advancement of Science in 2010; and of the American Academy of Arts and Sciences in 2017. In 2021, he received an honorary degree in economics from the University of Athens, Greece. He was awarded the Barry Prize for Distinguished Intellectual Achievement by the American Academy of Sciences and Letters in 2024. In 2009, Christakis was named to the Time 100, Time magazine's list of the 100 most influential people in the world. In 2009 and again in 2010, he was named by Foreign Policy magazine to its list of top global thinkers.