Messmer High School is a private, Roman Catholic high school in Milwaukee, Wisconsin, United States. It is located in the Roman Catholic Archdiocese of Milwaukee.Messmer High School was established in 1926 as Diocesan High School. It was renamed after Archbishop Sebastian Messmer in 1928.Notable alumni Bob Heinz, former NFL football player who played for the Miami Dolphins and the Washington Redskins John "JJ" Johnson, NBA basketball player Ronald G. Parys, Wisconsin State Assemblyman and Senator Ishmael "IshDarr" Ali, Rapper.