William I, known as William the Conqueror, was born around 1028 in Falaise, Normandy. He was the illegitimate son of Robert I, Duke of Normandy, and Herleva, a tanner's daughter. This birth outside of wedlock earned him the nickname "William the Bastard." His early years were marked by turmoil, as his status as a bastard son made him a target in the often treacherous political landscape of Normandy. After his father's death during a pilgrimage, young William faced numerous challenges, including assassination attempts and rebellions, as various factions tried to usurp his claim to the ducal throne.

Ascending as the Duke of Normandy, William consolidated his power through astute political maneuvers and military campaigns. His claim to the English throne came through his distant kinship with Edward the Confessor and a purported promise of the throne. When Harold Godwinson was crowned king in 1066, William contested the ascension, culminating in the famous Battle of Hastings where King Harold was defeated and killed. This victory and subsequent campaigns allowed William to establish himself as King of England, changing the course of English history.

William's reign (1066-1087) was characterized by profound structural changes in governance, land ownership, and society. To control and oversee his new kingdom, he commissioned the Domesday Book in 1086, an extensive survey detailing landholdings and resources. This document showcased the thoroughness with which William approached governance and provided a blueprint for taxation.

Relationships with the English governing class were initially tense. The Anglo-Saxon nobility was largely dispossessed, replaced by Norman landholders loyal to William. There was no formalized "Parliament" during William's time, but he convened councils and held courts to manage state affairs. The English populace had mixed feelings towards him. While some viewed him as a foreign oppressor, others acknowledged the stability and structure he brought after years of contention for the throne.

Foreign relations under William were complicated, often defined by territorial ambitions and defense of his dual roles as both King of England and Duke of Normandy. This often brought him into conflict with the French monarchy and other European leaders.

On the familial front, William married Matilda of Flanders, and together they had several children, including future kings William II and Henry I. While familial relations during this period were often political, there's evidence to suggest that William and Matilda shared a bond of genuine affection.

William's demise in 1087 came after a fall from a horse during a siege in France. He died in Rouen, Normandy, and his body was transported to Caen for burial. His death marked the end of a transformative era in English history. The immediate response to his death among the English was mixed. While many in England resented Norman rule, it's undeniable that William's reign brought significant political, cultural, and structural changes.

Culturally, the Norman Conquest introduced French linguistic, architectural, and societal influences to England. The construction of Romanesque and Norman-style stone churches, cathedrals, and castles, such as the Tower of London, became prominent. The fusion of Anglo-Saxon and Norman traditions over the subsequent centuries significantly impacted English language, governance, and culture. This period was foundational, setting the stage for the evolution of the English monarchy and its global influence in the centuries to come.