Leonard S. Baker (January 24, 1931 – November 23, 1984) was an American writer.
He won the 1979 Pulitzer Prize for Biography or Autobiography for Days of Sorrow and Pain: Leo Baeck and the Berlin Jews (Oxford University Press, ISBN 0-19-502800-7), a book about Leo Baeck.
His other published works include The Johnson Eclipse: A President's Vice Presidency, Back to Back: The Duel Between FDR and the Supreme Court, John Marshall: A Life in Law, Brandeis and Frankfurter: A Dual Biography, Brahmin in Revolt, Roosevelt and Pearl Harbor, and The Guaranteed Society.
A 1952 graduate of the University of Pittsburgh's School of Arts and Sciences, Baker served as a reporter for the St. Louis Globe-Democrat from 1955–1956 and for Newsday from 1956-1965.He also married and had two children: David Baker and Sara Baker.