Karl Joseph von Firmian (15 August 1716 – 20 July 1782) was an Austrian noble, who served as Plenipotentiary of Lombardy to the Habsburg Monarchy.

He was raised and educated in the Abbey School of Ettal in Bavaria, then in Innsbruck and Salzburg.

He is remembered as an avid promoter of the arts and sciences, patronizing both the artists Johann Joachim Winckelmann and Angelica Kauffman.

From the painter Andrea Salvatore Aglio, he commissioned a Virgin of Bovilli and a Birth of Maria de Medici, Queen of France, copy of the large canvas by Rubens.

During the Napoleonic occupation of Lombardy, his monument was removed as part of an effort to expunge any signs of prior Austrian governance.