Ælfgifu of Northampton (c. 990 – after 1036) was the first wife of Cnut the Great, King of England and Denmark, and mother of Harold Harefoot, King of England. She was regent of Norway from 1030 to 1035.

Ælfgifu was born into an important noble family based in the Midlands (Mercia). She was a daughter of Ælfhelm, ealdorman of southern Northumbria, and his wife Wulfrune. Ælfhelm was killed in 1006, probably at the command of King Æthelred the Unready, and Ælfgifu's brothers, Ufegeat and Wulfheah, were blinded. Wulfric Spot, a wealthy nobleman and patron of Burton Abbey, was the brother of Ælfhelm or Wulfrune. The family again came under suspicion during the invasion of England by Swein Forkbeard, King of Denmark, in 1013–14, and further members were charged with treachery and killed.^[1]

When Swein invaded, northern peoples, many of them of Scandinavian descent, immediately submitted to him. He then married his young son Cnut to Ælfgifu to seal their loyalty. Swein went on to conquer the whole of England and was accepted as King, but he died in February 1014 after a reign of only five weeks. Æthelred then sent an army which forced Cnut to flee back to Denmark, and in the opinion of historian Ian Howard, he left his wife and their baby son, Svein, the future King of Norway, behind with her family. They were anxious to make their peace with Æthelred, but unwilling to hand Ælfgifu and her son over to Æthelred to be killed, so they sent the mother and child with King Swein's body to Denmark. There she became pregnant again and in 1015 or 1016 she gave birth to Harold Harefoot.^[2]

In the period immediately following, she may have been given authority over some region of Denmark, perhaps that of a Danish controlled area of the Baltic coastline.^[3]

Her two sons were to figure prominently in the empire which their father built in northern Europe, though not without opposition. After his conquest of England in 1016, Cnut married Emma of Normandy, the widow of King Æthelred. It was then regarded as acceptable to put aside one wife and take another if the first wife was acquired through the non-Christian pagan ceremony of "handfasting" and nearly always for reasons of political advantage, a practice which might be described as "serial monogamy"; this was the case with the marriage of Ælfgifu to Cnut.^[4][5] The status of Cnut's two 'marriages' and their social context in England and Scandinavia has been discussed recently by Timothy Bolton.^[6] Emma's sons, Edward and Ælfred by Æthelred and Harthacnut by Cnut, were also claimants to the throne of her husband. Exactly how the second marriage affected Ælfgifu's status as Cnut's first consort is unknown, but there is no evidence to suggest that she was repudiated.

After the defeat and death of Olaf II of Norway by forces loyal to Cnut, Cnut sent Ælfgifu with their eldest son Svein to rule Norway, in 1030. Their rule was, however, so harsh that the Norwegians rebelled against them. They were driven out, in 1034 or 1035, while Svein died of wounds in Denmark shortly after, probably in 1036. In Norway, where she was known as Álfífa in Old Norse, this period entered history as 'Álfífa's time'(Álfífuǫld), remembered for her severe rule and heavy taxation. In the Norwegian Ágrip, for instance, the following verse is attributed to her contemporary, the skald Sigvatr:

Cnut died at Shaftesbury in 1035. Symeon of Durham and Adam of Bremen suggest that Cnut had reserved the English throne for Harold, while the Encomium Emmae Reginae, written to defend Harthacnut's mother, Emma, claims that he had done so for Harthacnut. Ælfgifu was determined that her second son Harold should be the next English king. She had returned to England (at least) by 1036, while Emma's son Harthacnut was away in Denmark, at war with the Norwegian king Magnus I, and the Swedes under their king Anund Jacob. Emma's other sons, Ælfred and Edward, stayed in Normandy. With help from her supporters, Ælfgifu was able to secure the throne for her son. In the view of Frank Stenton, she was probably the real ruler of England for part, if not the whole, of his reign.^[8]

The Anglo-Saxon Chronicle (versions C, D and E) describes how Harold and his men forcefully laid claim on the treasury housed in Winchester, where Cnut was buried and Emma (whom the Anglo-Saxons also referred to as "Ælfgifu" the queen) had taken up residence:

Manuscript E, which is known for its Godwinist sympathies, adds a number of details, including the assembly at Oxford in 1037 at which Harold was elected king of England and the mustering of support north of the Thames, where the power base of Ælfgifu's family was concentrated.

During 1036 opinion in England moved towards Harold. By August a report had reached Emma's daughter, Gunnhild, at the German court that her "unhappy and unjust step-mother" (i.e. Ælfgifu) was working to deprive Gunnhild's brother, Harthacnut, of the kingdom by holding great feasts, and trying by argument and gifts to persuade the leading nobles to give their fealty to Harold.^[11] Emma's encomiast attributes to her even more seriously dishonest methods. She makes Ælfgifu an accomplice in the murder of Emma's youngest son, Alfred, by suggesting that she was responsible for sending a forged letter to Normandy inviting Alfred to England. The Encomium Emmae Reginae also claimed that Ælfgifu's son Harold was a servant's son.

Ælfgifu is not recorded after 1036, apart from a possible reference to her as the "lady", and it is not known when she died.^[1]