Joseph Xaver Liesganig (13 February 1719 – 4 March 1799) was a Jesuit priest and geodesist who was a professor of mathematics at the University of Vienna. He taught mathematics from 1742 at the University of Graz. He was involved in measuring the extent of Austria, establishing the longitude of Vienna and in early trigonometrical mapping of the region. He was the last of the Jesuit astronomers at the Vienna observatory.