George IV (George Augustus Frederick) was king of the United Kingdom of Great Britain and Ireland and Hanover from 29 January 1820 until his death on 26 June 1830. He had earlier served as The Prince Regent when his father, George III, suffered from a relapse into insanity from an illness that is now suspected to have been porphyria. The Regency, George's nine-year tenure as Prince Regent, which commenced in 1811 and ended with George III's death in 1820, was marked by victory in the Napoleonic Wars in Europe.

George was a stubborn monarch, often interfering in politics, especially in the matter of Catholic emancipation, though not as much as his father. For most of George's regency and reign, Lord Liverpool controlled the government as Prime Minister.

George is remembered largely for the extravagant lifestyle that he maintained as prince and monarch. By 1797 his weight had reached 17 stone 7 pounds (111 kg or 245 lb), and by 1824 his corset was made for a waist of 50 inches (127 cm). He had a poor relationship with both his father and his wife, Caroline of Brunswick, whom he even forbade to attend his coronation. He was a patron of new forms of leisure, style and taste. He commissioned architects John Nash to build the Royal Pavilion in Brighton and remodel Buckingham Palace, and Sir Jeffry Wyatville to rebuild Windsor Castle. He was largely instrumental in the foundation of the National Gallery, London and King's College London.

William IV (William Henry) was King of Hanover and of the United Kingdom of Great Britain and Ireland from 26 June 1830 until his death on 20 June 1837. William, the third son of George III and younger brother and successor to George IV, was the last king and penultimate monarch of the House of Hanover.

He served in the Royal Navy in his youth and was, both during his reign and afterwards, nicknamed the Sailor King. He served in North America and the Caribbean, but saw little actual fighting. Since his two older brothers died without leaving surviving legitimate issue, he inherited the throne when he was sixty-four years old. His reign saw several reforms: the poor law was updated, child labour restricted and slavery abolished throughout the British Empire. One of the most important pieces of legislation was the Reform Act 1832, which refashioned the British electoral system. Though William did not engage in politics as much as his brother or his father, he was the last monarch to appoint a Prime Minister contrary to the will of Parliament. During his reign, his other kingdom, Hanover, was granted a short-lived liberal constitution.

At his death William had no surviving legitimate children, though he was survived by eight of the ten illegitimate children he had by the popular actress, Dorothea Bland, better known as Mrs. Jordan, with whom he cohabited for twenty years. He was succeeded in the United Kingdom by his niece, Victoria, and in Hanover by his brother, Ernest Augustus.

From the age of 12 George served in the Royal Navy, but upon the unexpected death of his elder brother, Prince Albert Victor, Duke of Clarence and Avondale, he became heir to the throne and married his brother's fiancée, Mary of Teck (known as "May" to her family after her birth month). Although they occasionally toured the British Empire, George preferred to stay at home with his stamp collection and lived what later biographers would consider a dull life because of its conventionality.

When George's father, King Edward VII died in 1910, he became King-Emperor. He was the only Emperor of India to be present at his own Delhi Durbar, where he appeared before his Indian subjects crowned with the Imperial Crown of India, created specially for the occasion. During World War I he relinquished all German titles and styles on behalf of his relatives who were British subjects; and changed the name of the royal house from Saxe-Coburg and Gotha to Windsor. During his reign, the Statute of Westminster separated the crown so that George ruled the dominions as separate kingdoms, preparing the way for the future development of the Commonwealth. His reign also witnessed the rise of socialism, fascism, Irish republicanism and the first Labour ministry, all of which radically changed the political spectrum.

As the second son of King George V, he was not expected to inherit the throne and spent his early life in the shadow of his elder brother, Edward. He served in the Royal Navy during World War I, and after the war took on the usual round of public engagements. He married Lady Elizabeth Bowes-Lyon in 1923, and they had two daughters, Elizabeth (who succeeded him as Queen Elizabeth II) and Margaret.

At the death of his father in 1936, the future George VI's brother ascended the throne as Edward VIII. However, less than a year later Edward expressed his desire to marry the twice-divorced American socialite Wallis Simpson. For political and religious reasons, the British Prime Minister, Stanley Baldwin, advised Edward that he could not marry Mrs Simpson and remain king. So, Edward abdicated in order to marry. By reason of this abdication, unique in the history of the British Isles (previous abdications were forced by military or political pressures), George VI ascended the throne as the third monarch of the House of Windsor.