Ronald Harold Johnson (born April 8, 1955) is an American businessman and far-right politician serving as the senior United States senator from Wisconsin, a seat he has held since 2011. A Republican, Johnson was first elected to the U.

S. Senate in 2010, defeating Democratic incumbent Russ Feingold. He was reelected in 2016, defeating Feingold in a rematch, and in 2022, narrowly defeating Lieutenant Governor Mandela Barnes.