| His Majesty|
20 September 1866
| George III|
12 October 1814
The King of Hanover (German: König von Hannover) was the official title of the head of state and hereditary ruler of the Kingdom of Hanover, beginning with the proclamation of the King of the United Kingdom George III, as "King of Hanover" during the Congress of Vienna, on 12 October 1814 at Vienna, and ending with the kingdom's annexation by Prussia on 20 September 1866.
King of Hanover Wikipedia
In 1813, George III of the United Kingdom was restored to his Hanoverian territories, and in October 1814 they were constituted as the independent Kingdom of Hanover at the Congress of Vienna. The personal union with the United Kingdom ended in 1837 on the accession of Queen Victoria because the succession laws in Hanover, based on Salic law, prevented a female inheriting the title if there was any surviving male heir (in the United Kingdom, a male took precedence only over his own sisters).George V, 20 September 1866 – 12 June 1878
Prince Ernest Augustus, 3rd Duke of Cumberland and Teviotdale, 12 June 1878 – 14 November 1923
Ernest Augustus, Duke of Brunswick, 30 January 1923 – 30 January 1953
Prince Ernest Augustus of Hanover (1914-1987), 30 January 1953 – 9 December 1987
Prince Ernest Augustus of Hanover (born 1954), 9 December 1987 - present
After the personal union with Great Britain ended in 1837, the monarchs of Hanover kept the British royal arms and standard, only introducing a new Crown (after the British model).