Bernard I Duke of Braunschweig-Lüneburg
- Born: Abt 1360
- Marriage: Margaret
- Died: 11 Jun 1434, Celle about age 74
Bernard (born between 1358 and 1364, died 11 June 1434, Celle), Duke of Brunswick-Lüneburg, ruled over several principalities of Brunswick-Lüneburg. In the genealogy of the House of Welf, he is considered the first member of the Second House of Lüneburg.
Bernard was the second son of Magnus II with the Necklace. After the death of his father in 1373, he and his brothers agreed with the Ascanian dukes of Saxony-Wittenberg to alternate rule in the Principality of Lüneburg. From 1375 on, Bernard took part in the government de jure, and from 1385 on de facto.
After their oldest brother, Friedrich, had been murdered in 1400, Bernard and his brother Heinrich (Henry) went on a revenge campaign against the Archbishopric of Mainz and the County of Waldeck, since the archbishop of Mainz was the suspected instigator of the murder plot, and the count of Waldeck performed the deed.
Bernard and Henry ruled the Principality of Brunswick together after Frederick's death; in a treaty of 1409, Bernard received sole rule over Brunswick. After a second treaty in 1428, Bernard switched to the Principality of Lüneburg.
Bernard married Margaret, daughter of Wenceslaus, Elector of Saxony, in 1386. They had three children:
* Otto (died 1446)
* Frederick (died 1478)
* Catherine (died 1429; did not marry)
Bernard married Margaret. (Margaret was born about 1370.)