Mellette County is a county in the state of South Dakota. The county seat is White River. The county was created in 1909, but not organized until 1911. The county is named after the first governor of the state, Arthur C. Mellette.
The County has two incorporated towns, White River and Wood. There are also the unincorporated communities of Norris, Mosher, and Cedar Butte. Mellette County currently has 14 organized townships.