Rodney Kohler "Rod" Johnston (September 2, 1937 – March 30, 2018) was an American attorney and Republican politician. He served six years in the Wisconsin State Senate (1979–1985) after four years in the State Assembly (1975–1979), representing suburban North Shore area of Milwaukee County. In 1982, he was the Republican nominee for United States Congress in Wisconsin's 5th congressional district, but was defeated by Jim Moody. In 1984, Johnston was challenged by Democrat Barbara Ulichny in the 4th Senate district. Ulichny prevailed in the general election, taking 55% of the vote.