The House of Hanover (German: Haus Hannover German pronunciation: [haʊ̯s haˈnoːfɐ]) is a European royal house with roots tracing back to the 17th century. Its members, known as Hanoverians, ruled Hanover, Great Britain, Ireland, and the British Empire at various times during the 17th to 20th centuries. Originating as a cadet branch of the House of Welf (also "Guelf" or "Guelph") in 1635, also known then as the House of Brunswick-Lüneburg, the Hanoverians ascended to prominence with Hanover's elevation to an Electorate of the Holy Roman Empire in 1692. In 1714 George I, prince-elector of Hanover and a descendant of King James VI and I, assumed the throne of Great Britain and Ireland, marking the beginning of Hanoverian rule over the British Empire. At the end of this line, Queen Victoria's death in 1901, the throne of the United Kingdom passed to her eldest son Edward VII, a member of the House of Saxe-Coburg and Gotha, through his father Albert, Prince Consort. The last reigning members of the House of Hanover lost the Duchy of Brunswick in 1918 when Germany became a republic and abolished royalty and nobility.

The formal name of the house was the "House of Brunswick-Lüneburg, Hanover line". The senior line of Brunswick-Lüneburg, which ruled Brunswick-Wolfenbüttel, became extinct in 1884. The House of Hanover is now the only surviving branch of the House of Welf, which is the senior branch of the House of Este. The current head of the House of Hanover is Ernst August, Prince of Hanover.

George, Duke of Brunswick-Lüneburg was the first member of the House of Hanover. When the Duchy of Brunswick-Lüneburg was divided in 1635, George inherited the Principality of Calenberg and moved his residence to Hanover. His son, Christian Louis, inherited the Principality of Lüneburg from George's brother. Calenberg and Lüneburg were then shared between George's sons until united in 1705 under his grandson, also called George, who subsequently became George I of Great Britain. All members held the title of Duke of Brunswick-Lüneburg.

George Louis became the first British monarch of the House of Hanover as George I in 1714. The dynasty provided six British monarchs:

Of the Kingdoms of Great Britain and Ireland (changed in 1801 to the United Kingdom of Great Britain and Ireland):

George I, George II, and George III also served as electors and dukes of Brunswick-Lüneburg, informally, Electors of Hanover (cf. personal union). They served as dual monarchs of Britain and Hanover, maintaining control of the Hanoverian Army and foreign policy. From 1814, when Hanover became a kingdom following the Napoleonic Wars, the British monarch was also King of Hanover.

Upon the death of William IV in 1837, the personal union of the thrones of the United Kingdom and Hanover ended. Succession to the Hanoverian throne was regulated by semi-Salic law (agnatic-cognatic), which gave priority to all male lines before female lines, and so it passed not to Queen Victoria but to her uncle, the Duke of Cumberland. In 1901, when Queen Victoria, the last British monarch provided by the House of Hanover, died, her son and heir Edward VII became the first British monarch of the House of Saxe-Coburg and Gotha. Edward took his family name from that of his father, Prince Albert of Saxe-Coburg-Gotha.

After the death of William IV in 1837, the following kings of Hanover continued the dynasty: