Koldun (Russian: Колдун) was an Uragan-class monitor built for the Imperial Russian Navy in Belgium in the mid-1860s. The design was based on the American Passaic-class monitor, but was modified to suit Russian engines, guns and construction techniques. She was one of two ships of the class to be built in Belgium and assembled in Russia. Spending her entire career with the Baltic Fleet, the ship was only active when the Gulf of Finland was not frozen, but very little is known about her service. She was stricken in 1900 from the Navy List, converted into a coal barge in 1903 and renamed Barzha No. 324. Abandoned by the Soviets in Finland in 1918, the ship was later scrapped by the Finns.