Józef Rudolf Kustroń (born October 16, 1892 in Stryj - died September 16, 1939 in the village of Ulazow, during the Polish September Campaign) was a Brigadier General of the Polish Army in the Second Polish Republic, commandant of the 21st Mountain Infantry Division.
Kustroń spent his childhood in the southern town of Nowy Sącz, where his family had settled. In high school, he was an active member of youth organizations fighting for Poland’s independence (see Partitions of Poland), such as the ZET Youth Association. In 1910 he began studying law and philosophy at the Jagiellonian University in Kraków, and two years later joined the paramilitary Riflemen's Association. After the outbreak of World War I, Kustron joined the Polish Legions, and was promoted to platoon commander in the Second Infantry Regiment of the Legions. On October 29, 1914, he was wounded during the Battle of Molotkowo and, after recuperating, was promoted to porucznik (lieutenant). Transferred to the 4th Infantry Regiment, he fought against the Russians in the area of Lublin, and in Volhynia, and was promoted to captain. After the Oath crisis, Kustron was demoted by the Austrians, and moved to an infantry regiment of the Austro-Hungarian Army. From 1917, he was an active member of the Polish Military Organisation, and in late autumn of 1918, he participated in the disarmament of Austrian troops in Kraków.