Gustavus Sessinghaus (* November 8, 1838 in Cologne, Prussia, † November 16, 1887 in St. Louis, Missouri ) was an American politician of German origin. In March 1883 he represented the State of Missouri for a day in the U.S. House of Representatives.
Gustavus Sessinghaus first attended the schools of his native Germany and later emigrated to the United States, where he settled in St. Louis and worked in the mill business. During the Civil War he was a member of a reserve unit in the army of the Union. Besides his work in the mill business Sessinghaus was also politically active as a member of the Republican Party.
Between 1878 and 1880 he was a member of the school board of St. Louis. In the congressional elections of 1880 he was defeated in the third constituency of the Missouri Democrat Richard Graham Frost. Sessinghaus but put against the outcome of the election opposition one. The Congress decided only on the penultimate day of the next legislative session, on 2 March 1883 in his favor. This Sessinghaus could exercise his mandate for one day only until the official end of the term on March 3, 1883. Since he had failed in the elections of 1882, he could no longer remain in Congress.
After his retirement from the U.S. House of Representatives sat Sessinghaus his work as Müller continued. He died on 16 November 1887 in St. Louis, where he was also buried.