This paper describes the life and work of Slovenia's best-known Jesuit Gabrijel Gruber. Commemorating Gruber on the 200th anniversary of his death, some unknown details of his work in Russia are published for the first time. Gruber, The Professor, taught Mathematics in Ljubljana, Belarus and St. Petersburg. Among his prominent students were Jurij Vega and several Russian artists. Gruber, The Educator, organised classes at the University of Vilna and presided over the Petersburg collegium. Gruber, The Engineer, designed the famous canal in Ljubljana, supervised half of the waterways constructions in the monarchy and designed sailboats and other ships. Gruber, The Architect, built a palace and a villa near Rožnik in Ljubljana, and several buildings in Polock and St. Petersburg. Gruber, The Natural Historian, researched geology and Karst water currents, earthquakes, magnetism and optical illusions. Gruber, The Priest, held free masses in the church of St. Catherine in St. Petersburg. Gruber, The Politician, led the Catholic side of the European diplomacy in the time of the first consul Napoleon.