Louis IV (German: Ludwig; 1 April 1282 – 11 October 1347), called the Bavarian, of the house of Wittelsbach, is King of the Romans from 1314, King of Italy from 1327, and Holy Roman Emperor from 1328.

Louis IV is Duke of Upper Bavaria from 1294/1301 together with his elder brother Rudolf I, serves as Margrave of Brandenburg until 1323, as Count Palatine of the Rhine until 1329, and becomes Duke of Lower Bavaria in 1340.

He obtains the titles Count of Hainaut, Holland, Zeeland, and Friesland in 1345 when his wife Margaret inherits them.