Empress Matilda (c. 7 February 1102 – 10 September 1167), also known as Empress Maud, was Holy Roman Empress as the consort of Emperor Henry V from 1110 until his death in 1125, and was subsequently a claimant to the English throne during the civil war known as the Anarchy. Following the death of her father, King Henry I of England, she asserted her right to the English throne as his only surviving legitimate child and styled herself Lady of the English. However, her cousin Stephen of Blois was crowned king in her place.

Matilda was the only daughter and eldest child of Henry I, king of England and ruler of Normandy, by his first wife Matilda of Scotland, to survive to adulthood. As a child, she went to Germany where she was married to the future Henry V. She travelled with the emperor to Italy in 1116, was controversially crowned empress in St Peter's Basilica, and acted as the imperial regent in Italy. Matilda and Henry V had no children, and when he died in 1125, the imperial crown was claimed by his rival Lothair of Supplinburg.

Matilda's younger and only full brother, William Adelin, died in the White Ship disaster of 1120, leaving Matilda's father and realm facing a potential succession crisis. Upon her widowhood in the Holy Roman Empire, Matilda was recalled to Normandy by her father, who arranged for her to marry Geoffrey of Anjou to form an alliance to protect his southern borders in France. Henry I had no further legitimate children and nominated Matilda as his heir, making his court swear an oath of loyalty to her and her successors, but the decision was not popular in his Anglo-Norman court. Henry died in 1135, but Matilda and Geoffrey faced opposition from the barons. Henry's nephew and successor, King Stephen, enjoyed the backing of the English Church. Stephen took steps to solidify his new regime but faced threats both from neighbouring powers and from opponents within his kingdom.

In 1139, Matilda crossed to England to take the kingdom by force, supported by her half-brother Robert, Earl of Gloucester, and her uncle David I of Scotland, while her husband, Geoffrey, focused on conquering Normandy. Matilda's forces captured Stephen at the Battle of Lincoln in 1141, but her attempt to be crowned at Westminster Abbey collapsed in the face of bitter opposition from the London crowds. As a result of this retreat, Matilda was never formally declared Queen of England, and was instead titled "Lady of the English" (Latin: domina Anglorum). Robert was captured following the Rout of Winchester in 1141, and Matilda agreed to exchange Stephen for him. Matilda was besieged at Oxford Castle by Stephen's forces that winter, but escaped at night across the frozen River Isis (Thames) to Abingdon. The war degenerated into a stalemate, with Matilda controlling much of the south-west of England, and Stephen the south-east and the Midlands. Large parts of the rest of the country were in the hands of local, independent barons.

Matilda returned to Normandy, now in the hands of her husband, in 1148, leaving their eldest son to continue the campaign in England; he was eventually declared Stephen's heir after the signing of the Treaty of Wallingford and succeeded to the throne as Henry II in 1154, forming the Angevin Empire. Matilda settled her court near Rouen and for the rest of her life concerned herself with the administration of Normandy, acting on her son's behalf when necessary. Particularly in the early years of her son's reign, she provided political advice and attempted to mediate during the Becket controversy. She worked extensively with the Church, founding Cistercian monasteries, and was known for her piety. She was buried under the high altar at Bec Abbey after her death in 1167, until much later when her tomb was moved to Rouen Cathedral.

Matilda was born to Henry I, King of England and Duke of Normandy, and his first wife, Matilda of Scotland, possibly on 7 February 1102 at Sutton Courtenay, in Berkshire. Henry was the youngest son of William the Conqueror, who had invaded England in 1066, creating an empire stretching into Wales. The invasion had created an Anglo-Norman elite, many with estates spread across both sides of the English Channel. These barons typically had close links to the Kingdom of France, which was then a loose collection of counties and smaller polities, under only the minimal control of the French king. Her mother Matilda was the daughter of Malcolm III of Scotland and Margaret of Wessex, a member of the West Saxon royal family, and a descendant of Alfred the Great. For Henry I, marrying Matilda of Scotland had given his reign increased legitimacy, and for her it had been an opportunity for high status and power in England.

Matilda had a younger, legitimate brother, William Adelin, and her father's relationships with numerous mistresses resulted in around 22 illegitimate siblings. Little is known about Matilda's earliest life, but she probably stayed with her mother, was taught to read, and was educated in religious morals. Among the nobles at the English court were her uncle David, later the king of Scotland, and aspiring nobles such as her illegitimate half-brother Robert of Gloucester, her cousin Stephen of Blois and Brian Fitz Count. In 1108, Henry left Matilda and William Adelin in the care of Anselm, the archbishop of Canterbury, while he travelled to Normandy; Anselm was a favoured cleric of Matilda's mother. There is no detailed description of Matilda's appearance; contemporaries described Matilda as being very beautiful, but this may have simply reflected the conventional practice among the chroniclers.

In late 1108 or early 1109, Henry V of Germany sent envoys to Normandy proposing that Matilda marry him, and wrote separately to her mother on the same matter. The match was attractive to the English king: his daughter would be marrying into one of the most prestigious dynasties in Europe, reaffirming his own, slightly questionable, status as the youngest son of a new royal house, and gaining him an ally in dealing with France. In return, Henry V would receive a dowry of 10,000 marks, which he needed to fund an expedition to Rome for his coronation as Holy Roman emperor. The final details of the deal were negotiated at Westminster in June 1109 and, as a result of her changing status, Matilda attended a royal council for the first time that October. She left England in February 1110 to make her way to Germany.