Ralph B. Guy, Jr. (born 1929) is a United States federal judge.
Born in Detroit, Michigan, Guy received an A.B. from the University of Michigan in 1951 and a J.D. from the University of Michigan Law School in 1953. He was in private practice in Dearborn, Michigan from 1954 to 1955. He was an assistant corporation counsel for the City of Dearborn from 1955 to 1958, and corporation counsel for that city until 1968. He was then a chief assistant U.S. Attorney for the Eastern District of Michigan until 1970, serving as the U.S. Attorney for the Eastern District of Michigan from until 1976.
On April 26, 1976, Guy was nominated by President Gerald Ford to a seat on the United States District Court for the Eastern District of Michigan vacated by Frederick William Kaess. Guy was confirmed by the United States Senate on May 11, 1976, and received his commission the following day.
On July 23, 1985, President Ronald Reagan elevated Guy to a new seat on the United States Court of Appeals for the Sixth Circuit created by 98 Stat. 333. He was again confirmed by the United States Senate on October 16, 1985, and received his commission the following day. He assumed senior status on September 1, 1994.