Frederick William Horn (August 21, 1815 – January 15, 1893) was a German-American immigrant, lawyer, politician, and Wisconsin pioneer. He served in many elected offices; he was the 4th, 7th, & 25th speaker of the Wisconsin State Assembly, and served a total of 14 years in the Assembly. He also served five years in the Wisconsin State Senate—including the first three sessions after statehood—and was the first mayor of Cedarburg, Wisconsin, serving seven years in that role. He generally identified as a Democrat, but was elected several times as an Independent.