John Woodland "Woody" Hastings, (March 24, 1927 – August 6, 2014) was a leader in the field of photobiology, especially bioluminescence, and was one of the founders of the field of circadian biology (the study of circadian rhythms, or the sleep-wake cycle). He was the Paul C. Mangelsdorf Professor of Natural Sciences and Professor of Molecular and Cellular Biology at Harvard University. He published over 400 papers and co-edited three books.