Henry III of Brunswick-Lüneburg

Henry III of Brunswick-Lüneburg (c. 1296–1363) was a Welf prince who held the bishopric of Hildesheim from 1331 against the will of the pope. Son of Duke Albert II of Brunswick-Göttingen, he was elected by the cathedral chapter in August 1331, but his predecessor had placed the bishopric in papal hands before dying, so confirmation was doubtful.

Pope John XXII appointed Count Erich of Holstein-Schaumburg instead and placed Henry, who refused to yield, under ban and interdict. With the chapter, the Brunswick dukes and the local nobility behind him, Henry controlled most of the bishopric, while Erich held little beyond the city and its monasteries. The schism lasted until about 1350.

In 1346–1349 he built the water castle of Marienburg near Hildesheim. He died in Hildesheim on 6 February 1363.