Edward VIII (Edward Albert Christian George Andrew Patrick David; 23 June 1894 28 May 1972), later known as the Duke of Windsor, was King of the United Kingdom and the Dominions of the British Empire and Emperor of India from 20 January 1936 until his abdication in December of the same year.Edward was born during the reign of his great-grandmother Queen Victoria as the eldest child of the Duke and Duchess of York, later King George V and Queen Mary. He was created Prince of Wales on his 16th birthday, seven weeks after his father succeeded as king. As a young man, Edward served in the British Army during the First World War and undertook several overseas tours on behalf of his father. While Prince of Wales, he engaged in a series of sexual affairs that worried both his father and then-British prime minister Stanley Baldwin.

Upon his father's death in 1936, Edward became the second monarch of the House of Windsor. The new king showed impatience with court protocol, and caused concern among politicians by his apparent disregard for established constitutional conventions. Only months into his reign, a constitutional crisis was caused by his proposal to marry Wallis Simpson, an American who had divorced her first husband and was seeking a divorce from her second. The prime ministers of the United Kingdom and the Dominions opposed the marriage, arguing a divorced woman with two living ex-husbands was politically and socially unacceptable as a prospective queen consort. Additionally, such a marriage would have conflicted with Edward's status as titular head of the Church of England, which, at the time, disapproved of remarriage after divorce if a former spouse was still alive. Edward knew the Baldwin government would resign if the marriage went ahead, which could have forced a general election and would have ruined his status as a politically neutral constitutional monarch. When it became apparent he could not marry Simpson and remain on the throne, he abdicated. He was succeeded by his younger brother, George VI. With a reign of 326 days, Edward was one of the shortest-reigning British monarchs to date.

After his abdication, Edward was created Duke of Windsor. He married Simpson in France on 3 June 1937, after her second divorce became final. Later that year, the couple toured Nazi Germany, which fed rumours that he was a Nazi sympathiser. During the Second World War, Edward was at first stationed with the British Military Mission to France but after the fall of France was appointed Governor of the Bahamas. After the war, Edward spent the rest of his life in France. He and Wallis remained married until his death in 1972; they had no children.

In 1936 a constitutional crisis in the British Empire arose when King-Emperor Edward VIII proposed to marry Wallis Simpson, an American socialite who was divorced from her first husband and was pursuing the divorce of her second.

The marriage was opposed by the governments of the United Kingdom and the Dominions of the British Commonwealth. Religious, legal, political, and moral objections were raised. As the British monarch, Edward was the nominal head of the Church of England, which at this time did not allow divorced people to remarry in church if their ex-spouses were still alive. For this reason, it was widely believed that Edward could not marry Simpson and remain on the throne. Simpson was perceived to be politically and socially unsuitable as a prospective queen consort because of her two previous marriages. It was widely assumed by the Establishment that she was driven by love of money or position rather than love for the King. Despite the opposition, Edward declared that he loved Simpson and intended to marry her as soon as her second divorce was finalised.

The widespread unwillingness to accept Simpson as the King's consort and Edward's refusal to give her up led to his abdication in December 1936. He was succeeded by his brother Albert, who became George VI. Edward was given the title of Duke of Windsor, and styled Royal Highness, following his abdication, and he married Simpson the following year. They remained married until his death 35 years later.