Leonard Williams Levy (April 9, 1923 – August 24, 2006) was an American historian, the Andrew W. Mellon All-Claremont Professor of Humanities and Chairman of the Graduate Faculty of History at Claremont Graduate School, California, who specialized in the history of basic American Constitutional freedoms. He was born in Toronto, Ontario, and educated at Columbia University, where his mentor for the Ph.D. degree was Henry Steele Commager.