George III (1738-1820) is remembered most for the loss of the American colonies during his reign. King George III was, up until the reign of Queen Victoria, England's longest-ruling monarch, ruling for 59 years and overseeing Britain's victory in the Seven Years' War. His final decade of life was marked by blindness and insanity, earning him the moniker of "Mad King George."
During what is collectively referred to as the "Georgian era" from 1714 to 1830, the Hanovers ruled Britain. The family hailed from the Electorate of Hanover, which was part of the Holy Roman Empire. George III was the first of the Hanovers to be born in England. His father was Frederick, Prince of Wales.
The loss of the American Revolution affected George III immensely, and he drafted but never delivered an abdication speech. After George III slipped into an illness in 1810, his son was soon given the title of Prince Regent. George III was deaf, blind and mad when he died a decade later. A 2005 analysis of his hair attributed arsenic poisoning to his decline in health.
Interestingly, the planet Uranus was initially named "Georgium sidus," which means "the Georgian Star" after George III. It was George III who had funded the development of the telescope that had led to the discovery of Uranus. The name was later changed.