Roger John Traynor (February 12, 1900 – May 14, 1983) was the 23rd Chief Justice of California (1964-1970) and an associate justice of the Supreme Court of California from 1940 to 1964. Previously, he had served as a Deputy Attorney General of California under Earl Warren, and an Acting Dean and Professor of UC Berkeley School of Law. He is widely considered to be one of the most creative and influential judges and legal scholars of his time.

A jurist noted for liberalism and activism, Traynor's 30-year career as California's 77th Justice coincided with tremendous demographic, social, and governmental growth in California and in the United States of America. Traynor believed (in the words of his biographer, G. Edward White) that "the increased presence of government in American life was a necessary and beneficial phenomenon." After his retirement from the California Supreme Court, Traynor spent the last years of his life as a professor at the UC Hastings College of Law.