Philip I, Duke of Brunswick-Grubenhagen

Philip I, Duke of Brunswick-Grubenhagen was a member of the House of Guelph. He was ruler of the Principality of Grubenhagen. He was the second son of Duke Albert II of Grubenhagen and his wife Elizabeth, née Countess of Waldeck. Philip was the last member of the Grubenhagen line to use the title Duke of Brunswick. His successors used the title Duke of Brunswick and Lüneburg, like most other princes of the House of Guelph.