Josua Ritter von Gietl, actually Johann Ritter von Gietl was a German landscape and genre painter of the Munich School.

Gietl was born in Munich, the son of the physician Franz Xaver von Gietl and his wife Anna Maria, née Pasch. After attending the Maximiliansgymnasium from 1858 to 1868, he initially studied law at the University of Munich, but then, from 1873, painting at the Royal Academy of Fine Arts in Munich. There, Johann Georg Hiltensperger and Wilhelm von Lindenschmit the Younger were his most important teachers; private instruction came from Adolf Heinrich Lier and his student Joseph Wenglein. From about 1880, he was a member of the Dachau artists' colony.

He was also active in the northern surroundings of Munich (Allach, Lohhof), in Upper Bavaria (Chiemsee) and in the Salzkammergut (Gosau). From 1883, he annually sent works to the exhibitions of the Munich Glass Palace and the Munich Art Association, from 1893 to the Great Berlin Art Exhibition and in 1886 to the anniversary exhibition of the Royal Academy of Arts in Berlin. In 1904, Gietl founded the “Verein Münchener Aquarellisten” (Munich Watercolor Society) together with Carl Strathmann, René Reinicke, Hans Beat Wieland, Wilhelm Jakob Hertling, Hugo Kreyssig, Max Eduard Giese, Rudolf Köselitz, Paul Leuteritz, Hans Gabriel Jentzsch, Fritz von Hellingrath and Karl Itschner.