Marshall Leach, Jr. (February 23, 1940 – November 20, 2010) was an American electrical engineer, educator, and audio designer, best known for his pioneering work in low-distortion audio amplifiers and electroacoustics. Born in Abbeville, South Carolina, he earned his B.S. (1962) and M.S. (1964) in Electrical Engineering from the University of South Carolina, and his Ph.D. (1972) in Electrical Engineering from the Georgia Institute of Technology.
Leach joined the Georgia Tech faculty in 1972 as an assistant professor, becoming an associate professor in 1976 and a full professor in 1983. He taught courses in analog electronics, operational amplifier design, audio engineering, electromagnetic compatibility, and electroacoustics, and helped develop Georgia Tech's graduate Acoustical Engineering Program. His research spanned low-noise electronic design, near-field acoustic and electromagnetic measurements, loudspeaker system design, and RF power amplifier development.