Vuka is a river in eastern Croatia, a right tributary of the Danube river. At , it is the 13th-longest river flowing through Croatia and it has a drainage area of .
The river is located in the region of Slavonia. It rises in the Krndija hills in the Osijek-Baranja County and flows eastwards through lowlands into the Vukovar-Srijem County. It empties into the Danube at the town of Vukovar, which is named for the river.
The ancient name of Pannonian Illyrians for Vuka was Volcos.