List of monarchs in Britain by length of reign
The following is a list, ordered by length of reign, of the monarchs of the United Kingdom of Great Britain and Northern Ireland, the United Kingdom of Great Britain and Ireland, the Kingdom of Great Britain, the Kingdom of England, the Kingdom of Scotland, the Kingdom of Ireland, and the Principality of Wales.
Queen Elizabeth II became the longest-reigning monarch in British history on 9 September 2015 when she surpassed the reign of her great-great-grandmother Queen Victoria. On 6 February 2017, she became the first British monarch to celebrate a Sapphire Jubilee, commemorating 65 years on the throne. On 6 February 2022, Elizabeth II became the first British monarch to reign for 70 years, and large-scale celebrations for her Platinum Jubilee occurred on 2 to 5 June. At her death aged 96 later that year, she had reigned for 70 years and 214 days.
Ten longest-reigning British monarchs
These are the ten longest-reigning monarchs in the British Isles for whom there is reliable recorded evidence. This list excludes Constantine II of Scotland who ruled for approximately 43 years from circa 900 to 943.Complete list of the unitary monarchy
On 1 May 1707, under the Acts of Union 1707, the Kingdom of England united with the Kingdom of Scotland as the Kingdom of Great Britain. Then, on 1 January 1801, the Kingdom of Great Britain united with the Kingdom of Ireland to become the United Kingdom of Great Britain and Ireland, becoming the United Kingdom of Great Britain and Northern Ireland by Act of Parliament in 1927 following the creation of the Irish Free State in 1922.Complete list of the kingdoms
England
Includes English monarchs from the installation of Alfred the Great as King of Wessex in 871 to Anne and the Acts of Union on 1 May 1707, when the crown became part of the Kingdom of Great Britain.Scotland
Includes Scottish monarchs from the installation of Kenneth I in 848 to Anne and the Acts of Union on 1 May 1707, when the crown became part of the Kingdom of Great Britain.List of the Principalities
Gwynedd (incomplete list)
The Principality of Gwynedd, located in northwest Wales, was one of the most prominent early medieval Welsh kingdoms. Its rulers were often acclaimed as "King of the Britons," symbolizing their influence over other Welsh territories and their resistance to external threats. Gwynedd faced repeated challenges, including civil wars, Saxon incursions, and Norman invasions, which gradually eroded its dominance. In 1216, it transitioned into the Principality of Wales, although the title "Prince of Wales" was not formally adopted until the 1240s under the leadership of Llywelyn ap Gruffudd, also known as Llywelyn the Last.Gwynedd’s heartland was the mountainous region of Snowdonia, which provided natural defenses and contributed to its resilience against invaders. The kingdom played a central role in preserving Welsh identity, language, and culture during a period of significant upheaval in Britain.
Gwynedd’s political and military structure helped shape the foundations of later Welsh governance. Its rulers, particularly under the House of Aberffraw, established enduring principles of leadership and unity that influenced medieval Welsh law and identity. As historian R. R. Davies notes in The Age of Conquest: Wales 1063–1415, Gwynedd stood as “the nucleus of Welsh political life,” embodying both resistance and renewal amid centuries of external pressure.