Ralph S. Locher was an American politician of the Democratic party who served as mayor of Cleveland, Ohio.

Born in Romania in 1914, Locher graduated from Bluffton College and was admitted to the Ohio bar. He became a close associate of Frank J. Lausche, later Governor of Ohio and U.S. Senator, who nurtured his career. They were instrumental in building the "cosmopolitan Democrats" movement of urban ethnic voters. Locher was law director of Cleveland, Ohio under Mayor Anthony J. Celebrezze Sr., and succeeded him as mayor in 1962, when Celebrezze was appointed United States Secretary of Health, Education, and Welfare by President John F. Kennedy.

Locher served two terms as mayor of Cleveland. Unfortunately, his tenure was marked by increasing racial tensions in the city, culminating in the Hough and Glenville Riots of the 1960s. Locher lost in the 1967 nonpartisan mayoral primary to Democrat Carl B. Stokes and Republican Seth Taft .

Locher went on to be elected a probate court judge in 1970, and was elected to the Ohio Supreme Court in 1977, serving two terms. He died in 2004.