Guillermo el Conquistador, also known as William the Conqueror, was the first Norman King of England. He was born in 1028 in Falaise, Normandy, and became Duke of Normandy in 1035. In 1066, he invaded England and defeated King Harold II at the Battle of Hastings, claiming the English throne. As king, Guillermo implemented significant changes in England, including the introduction of the feudal system and the commissioning of the Domesday Book, a comprehensive survey of his new kingdom. His reign marked the beginning of Norman rule in England, which had lasting effects on the country's culture and governance.