英国君主由苏格兰王国与英格兰王国共组大不列颠王国开始计算，大不列颠王国、大不列颠及爱尔兰联合王国和大不列颠及北爱尔兰联合王国共有12名君主（见英国君主）。自1603年3月24日以来英格兰王国与苏格兰王国便处于斯图亚特王朝统领的共主邦联之下，而1707年5月1日这两国正式合并，创建大不列颠王国。1801年1月1日，大不列颠王国同爱尔兰王国合并，创建大不列颠及爱尔兰联合王国。1922年12月6日，爱尔兰大部脱离联邦；1927年4月12日该国因此更名为大不列颠及北爱尔兰联合王国。

There have been 12 monarchs of Great Britain and the United Kingdom (see the Monarchy of the United Kingdom). A new Kingdom of Great Britain was formed on 1 May 1707 with the merger of the Kingdom of England and the Kingdom of Scotland, which had been in personal union under the House of Stuart since 24 March 1603. On 1 January 1801, Great Britain merged with the Kingdom of Ireland (also previously in personal union with Great Britain) to form the United Kingdom of Great Britain and Ireland. After most of Ireland left the union on 6 December 1922, its name was amended on 12 April 1927 to the United Kingdom of Great Britain and Northern Ireland.