William Tallant Greenough (October 11, 1944 – December 18, 2013) was a professor of psychology at the University of Illinois at Urbana–Champaign. Greenough was a pioneer in studies of neural development and brain plasticity. He studied learning and memory and the brain's responses to environmental enrichment, exercise, injury, and aging. He demonstrated that the brain continues to form new synaptic connections between nerve cells throughout life in response to environmental enrichment and learning. This mechanism is fundamental to learning and memory storage in the brain. Greenough is regarded as the predominant researcher in this area and has been described as "one of the towering figures in neuroscience".