Charlotte of Mecklenburg-Strelitz (Sophia Charlotte; 19 May 1744 17 November 1818) was Queen of Great Britain and of Ireland as the wife of King George III from their marriage on 8 September 1761 until the union of the two kingdoms on 1 January 1801, after which she was Queen of the United Kingdom of Great Britain and Ireland until her death in 1818. As George's wife, she was also Electress of Hanover until becoming Queen of Hanover on 12 October 1814, when the electorate became a kingdom. Charlotte was Britain's longest-serving queen consort.

Charlotte was born into the royal family of Mecklenburg-Strelitz, a duchy in northern Germany. In 1760, the young and unmarried George III inherited the British throne. As Charlotte was a minor German princess with no interest in politics, George considered her a suitable consort, and they married in 1761. The marriage lasted 57 years and produced 15 children, 13 of whom survived to adulthood. They included two future British monarchs, George IV and William IV; as well as Charlotte, Princess Royal, who became Queen of Wrttemberg; Prince Edward, the father of Queen Victoria; Prince Adolphus, grandfather of the British queen consort Mary of Teck; and Prince Ernest Augustus, who became King of Hanover.

Charlotte was a patron of the arts and an amateur botanist who helped expand Kew Gardens. She introduced the Christmas tree to Britain, after decorating one for a Christmas party for children from Windsor in 1800. She was distressed by her husband's bouts of physical and mental illness, which became permanent in later life. She maintained a close relationship with Queen Marie Antoinette of France, and the French Revolution likely enhanced the emotional strain felt by Charlotte. Her eldest son, George, was appointed as Prince Regent in 1811 due to the increasing severity of the King's illness. Charlotte died in November 1818 with her son George at her side. Charlotte's husband, who was likely unaware of her death, died a little over a year later.

George III (George William Frederick; 4 June 1738 – 29 January 1820) was King of Great Britain and of Ireland from 25 October 1760 until the union of the two kingdoms on 1 January 1801, after which he was King of the United Kingdom of Great Britain and Ireland until his death in 1820. He was concurrently Duke and Prince-elector of Brunswick-Lüneburg ("Hanover") in the Holy Roman Empire before becoming King of Hanover on 12 October 1814. He was a monarch of the House of Hanover but, unlike his two predecessors, he was born in Great Britain, spoke English as his first language and never visited Hanover.George's life and reign, which were longer than those of any of his predecessors, were marked by a series of military conflicts involving his kingdoms, much of the rest of Europe, and places farther afield in Africa, the Americas and Asia. Early in his reign, Great Britain defeated France in the Seven Years' War, becoming the dominant European power in North America and India. However, many of Britain's American colonies were soon lost in the American War of Independence. Further wars against revolutionary and Napoleonic France from 1793 concluded in the defeat of Napoleon at the Battle of Waterloo in 1815. In 1807, the transatlantic slave trade was banned from the British Empire.

In the later part of his life, George had recurrent, and eventually permanent, mental illness. Although it has since been suggested that he had bipolar disorder or the blood disease porphyria, the cause of his illness remains unknown. George suffered a final relapse in 1810, and his eldest son, the Prince of Wales, became Prince Regent the following year. When George III died in 1820, the Regent succeeded him as King George IV. Historical analysis of George III's life has gone through a "kaleidoscope of changing views" that have depended heavily on the prejudices of his biographers and the sources available to them.