Guillaume le Conquérant, 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. William's reign marked significant changes in England, including the introduction of Norman culture and the feudal system. He commissioned the Domesday Book, a comprehensive survey of his new kingdom, which provided valuable information about land ownership and resources. William ruled until his death in 1087.