Dean O. Mehlhaff (June 28, 1927 – April 27, 2016) was an American politician in the state of South Dakota.

He was a member of the South Dakota House of Representatives from 1967 to 1976.

[1] He served in the United States Army and was a president of the Eureka Chamber of Commerce.

He worked in banking and insurance.

[2] He died on April 27, 2016, aged 88.