Juliusz Fortunat Kossak (Nowy Wiśnicz, 15 December 1824 – 3 February 1899, Kraków) was a Polish historical painter and master illustrator who specialized in battle scenes, military portraits and horses. He was the progenitor of an artistic family that spanned four generations, father of painter Wojciech Kossak and grandfather of painter Jerzy Kossak.
Juliusz Kossak grew up in Lwów during the military partitions of Poland. He obtained a degree in law at the Lwów University encouraged by his mother. At the same time he studied painting with Jan Maszkowski and Piotr Michałowski. Beginning in 1844 Kossak worked on commissions for the local aristocracy in Malopolska, Podolia and Wolyn. He married Zofia Gałczyńska in 1855 and together they left for Paris where they spent five years. His sons were born there, the twin brothers: Wojciech and Tadeusz (on New Year's Eve 1856–1857) and the younger Stefan in 1858. The family came to Warsaw in 1860 where Kossak obtained a position as the head illustrator and engraver for Tygodnik Illustrowany magazine. They moved to Munich for a year and in 1868 settled in Kraków blessed with five children already. Kossak bought a small estate there, known as Kossakówka, famed for artistic and literary salon frequented by Adam Asnyk, Henryk Sienkiewicz, Stanisław Witkiewicz, Józef Chełmoński and many others. Juliusz Kossak lived and worked there till the end of his life. In 1880 he was awarded the Cross of Order of Merit by Emperor Franz Joseph of Austria–Hungary for his lifetime achievements as an artist.
Kossak exhibited his work on Polish soil and abroad since 1854. His preferred medium was watercolour, both in smaller and larger formats. He was the precursor of a Polish school of battle-scene painting, with his main subject matter revolving around what was of great concern to Poles opposing the military occupation of their country. He was the author of over a dozen panoramic paintings depicting Polish cavalry in battle and on military actions against foreign invaders.