John Clark Ketcham (January 1, 1873 – December 4, 1941) was a politician from the U.S. state of Michigan.
Ketcham was born in Toledo, Ohio, and moved with his parents to Maple Grove, Michigan near Nashville, the same year. He attended the common schools of Barry County and high school at Nashville. He taught in rural and high schools from 1890 to 1899. Ketcham was county commissioner of schools for Barry County, 1899-1907, and chairman of the Republican county committee, 1902-1908. He was postmaster of Hastings, 1907-1914; master of the Michigan State Grange, 1912-1920; and lecturer of the National Grange, 1917-1921.
Ketcham was president of the National Bank of Hastings, 1933-1937; State commissioner of insurance, 1935-1937; and counsel for the Michigan Chain Store Bureau, 1938-1941. He died in Hastings and was interred there in Riverside Cemetery.