Monarchs of Great Britain and the United Kingdom (1707–2009)

The Act of Union between England and Scotland, creating the kingdom of Great Britain, came into effect on 1 May 1707. However, the title king of Great Britain, France, and Ireland had already been adopted by James VI and I on 20 Oct 1604, and was used in a variety of contexts in both England and Scotland by James and all his successors up to and beyond the Act of Union, although it was only that act that gave it legal force.

Between 1714 and 1837 the British monarch was also the ruler of the German state of Hanover; until 1814 the ruler was known as an elector, and afterwards as a king.

During the nineteenth century further constitutional changes reshaped the royal titles. The Act of Union, 1800, united Great Britain and Ireland under a single legislature from 1 Jan 1801; George III then became king of the United Kingdom of Great Britain and Ireland.

Subsequent changes related to the need to recognize the existence of imperial territories outside the British Isles. Victoria became empress of India in 1877. Edward VII became king of the British dominions beyond the seas in addition to his other titles in 1901.

In the twentieth century alterations in the royal style resulted from the independence of Ireland and the emergence of the Commonwealth from the British empire. In 1927, six years after the establishment of the Irish Free State, George V became king of the separate kingdoms of Great Britain and Ireland, presumably to emphasize the idea that although the Irish Free State and the United Kingdom of Great Britain and Northern Ireland were separate legislative entities, Ireland remained a united entity within the king's dominions. The independence of India in 1947 led George VI to abandon the title emperor of India; Éire, formerly the Irish Free State, became the Republic of Ireland outside the Commonwealth in 1949. The Royal Titles Act of 1953 instituted separate titles for each individual territory over which the British monarch reigned, so Elizabeth II became queen of the United Kingdom of Great Britain and Northern Ireland

The list is ordered chronologically by date of accession.