Marvin E. "Marv" Diemer (May 30, 1924 – April 23, 2013) was an American businessman and legislator. Born in New Auburn, Minnesota, Diemer served in the United States Marine Corps during World War II. He graduated from Drake University in 1950 and was a public accountant in Cedar Falls, Iowa. He served in the Iowa House of Representatives as a Republican 1979–1991. He died in Cedar Falls, Iowa.