Gregory Louis Possehl (July 21, 1941 – October 8, 2011) was a Professor Emeritus of Anthropology at the University of Pennsylvania and curator of the Asian Collections at the University of Pennsylvania Museum of Archaeology and Anthropology. He has been involved in excavations of the Indus Valley Civilization in India and Pakistan since 1964, and is an author of many books and articles on the Indus Civilization and related topics. He received his BA in Anthropology from the University of Washington in 1964, his MA in Anthropology from the University of Washington in 1967, and his PhD in Anthropology from the University of Chicago in 1974. He has conducted major excavations in Gujarat (Rojdi, Babar Kot and Oriyo Timbo), Rajasthan (Gilund), and in January 2007, began an excavation at the UNESCO World Heritage site of Bat in the Sultanate of Oman.

He is an exponent of the view that the culture of the Vedic period is a direct successor of the Indus Valley Civilization. In his book Ancient Cities of the Indus he writes that "the first point to be emphasized is that the problem seems not to be best stated as the "end" of a civilization, at least in the sense of a tradition, since there are abundant signs of cultural continuity in Sindh, Gujarat, the Punjab and adjacent areas of the North India."