William A. Cassidy (1928-2020) was an American geologist and professor emeritus of geology and planetary science at the University of Pittsburgh. He was responsible for recognizing that Antarctica represented the greatest repository of meteorites on Earth, led most major meteorite expeditions to the south polar region starting in the early 1970s, and was awarded the Antarctica Service Medal in 1979. He is credited with reports of the Antarctic Meteorite Location and Mapping Project (AMLAMP).