Rodney Kohler ("Rod") Johnston was an American politician who served in the Wisconsin State Assembly from 1975 to 1979 and in the Wisconsin State Senate from 1979 to 1985. He was a Republican.
In 1982, he ran for the United States House of Representatives from Wisconsin's 5th congressional district, losing to Jim Moody.
Johnston was born in Milwaukee, Wisconsin. He was a graduate of the United States Naval Academy and George Washington University Law School.
Johnston died March 30, 2018, at his home on Tybee Island, Georgia; he was 80 years old. He was survived by his three children, Scott, Julie, and actress Kristen Johnston.