Ernest of Brunswick-Lüneburg, also frequently called Ernest the Confessor, was duke of Brunswick-Lüneburg and a champion of the Protestant cause during the early years of the Protestant Reformation. He was the Prince of Lüneburg and ruled the Lüneburg-Celle subdivision of the Welf family's Brunswick-Lüneburg duchy from 1520 until his death.

The Principality of Lüneburg was a territorial division of the Duchy of Brunswick-Lüneburg within the Holy Roman Empire, immediately subordinate to the emperor. It existed from 1269 until 1705 and its territory lay within the modern-day state of Lower Saxony in Germany. The principality was named after its first capital, Lüneburg, which was ruled jointly by all Brunswick-Lüneburg lines until 1637. From 1378, the seat of the principality was in Celle. It lost its independence in 1705 when it was annexed by the Electorate of Brunswick-Lüneburg, but retained its vote in the Reichstag as Brunswick-Celle.