Sweyn Forkbeard in the context of "House of Knýtlinga"

Emma of Normandy (referred to as Ælfgifu in royal documents; c. 984 – 6 March 1052) was a Norman-born noblewoman who became the English, Danish, and Norwegian Queen through her marriages to the Anglo-Saxon King Æthelred the Unready and the Danish King Cnut the Great. A daughter of the Norman ruler Richard the Fearless and Gunnor, she was Queen of England during her marriage to King Æthelred from 1002 to 1016, except during a brief interruption in 1013–14 when the Danish King Sweyn Forkbeard occupied the English throne. Æthelred died in 1016, and Emma married Sweyn's son Cnut. As Cnut's wife, she was Queen of England from their marriage in 1017, Queen of Denmark from 1018, and Queen of Norway from 1028 until Cnut died in 1035.

After Cnut's death, Emma continued to participate in politics during the reigns of her sons by each husband, Harthacnut and Edward the Confessor. In 1035 when her second husband Cnut died and was succeeded by their son Harthacnut, who was in Denmark at the time, Emma was designated to act as his regent until his return, which she did in rivalry with Harold Harefoot. Emma is the central figure within the Encomium Emmae Reginae, a critical source for the history of early-11th-century English politics. As Catherine Karkov notes, Emma is one of the most visually represented early medieval queens.

Edmund Ironside (c. 990 – 30 November 1016; Old English: Ēadmund, Old Norse: Játmundr, Latin: Edmundus; sometimes also known as Edmund II) was King of the English from 23 April to 30 November 1016. He was the son of King Æthelred the Unready and his first wife, Ælfgifu of York. Edmund's reign was marred by a war he had inherited from his father; his epithet "Ironside" was given to him "because of his valour" in resisting the Danish invasion led by Cnut.

In the summer of 1013 Sweyn Forkbeard launched a full-scale invasion of England, driving out Aethelred by the end of the year. Edmund and his elder brother Aethelstan did not follow their father in exile. Sweyn died unexpectedly in February of 1014, and Æthelred was able to quickly reclaim the throne, driving out Sweyn's son Cnut, whom the Danes elected king. Aethelstan had died by June of 1014, making Edmund heir apparent.

The North Sea Empire, also known as the Anglo-Scandinavian Empire, was the personal union of the kingdoms of England, Denmark and Norway for most of the period between 1013 and 1042 towards the end of the Viking Age. This ephemeral Norse-ruled empire was a thalassocracy, its components only connected by and dependent upon the sea.

The first king to unite all three kingdoms was Sweyn Forkbeard, king of Denmark since 986 and of Norway since 1000, when he conquered England in 1013. He died in the following year, and his realm was divided. His son Cnut the Great acquired England in 1016, Denmark in 1018 and Norway in 1028. He died in 1035 and his realm was again divided, but his successor in Denmark, Harthacnut, inherited England in 1040 and ruled it until his death in 1042. At the height of his power, when Cnut ruled all three kingdoms (1028–1035), he was the most powerful ruler in western Europe after the Holy Roman Emperor.

Harald Svendsen (c. 996–998 − c. 1018) was King of Denmark (being Harald II) from 1014 until his death in c. 1018. He was the youngest son of Sweyn Forkbeard and Gunhild of Wenden, and was regent while his father was fighting Æthelred the Unready in England. After his father's death, he was elected to the Danish throne in 1014, while his brother, the later king Cnut the Great was elected to the throne of England. After his death in 1018(?), he was succeeded by Cnut the Great. Little detail is known about Harald II.

Estrid Svendsdatter of Denmark (also known as Estrith or Astrith; sometimes called Margaret; fl. 1017–1032; c. 990s – after 1057 and before 1073) was a prominent Danish princess and titular queen of the Jelling dynasty, half-sister of Cnut the Great and wife of the magnate Ulf Jarl. She was the mother of Sweyn II Estridsen, during whose reign she was commonly styled dronning (“queen”) in Denmark, though she was never queen regnant nor a king's consort. Through Estrid, Sweyn traced his claim to the Danish throne and founded the matronymic House of Estridsen, which ruled from 1047 to 1412.

Medieval sources diverge on several points of her life. She was a daughter of Sweyn Forkbeard, but her mother is variously identified in sources as Sigrid the Haughty or, in earlier scholarship, as the Slavic princess sometimes called Gunhild of Wenden, a view now generally rejected. After Sweyn's death in 1014, Estrid came under Cnut's guardianship. He married her to a son of Grand Prince Vladimir the Great or Yaroslav the Wise, but the prince died shortly afterwards. Several western chroniclers, including Rodulfus Glaber and Adam of Bremen, record a proposed or short-lived marriage with the duke of Normandy (probably Robert I, Duke of Normandy), though the precise details remain uncertain. By the early 1020s, she was married to the English magnate Ulf Thorgilsson, who later served as regent in Denmark. By marriage she was thus, successively, a Russian princess, duchess of Normandy and a Danish noblewoman.

In the autumn of 1016, the Danish prince Cnut the Great (Canute), supported by Eiríkr Hákonarson, and Thorkell the Tall successfully invaded England. Cnut's father, Sweyn Forkbeard, had previously conquered and briefly ruled England for less than five weeks.

Æthelstan Ætheling (Old English: Æþelstan Æþeling; early or mid 980s – 25 June 1014) was the eldest son of King Æthelred the Unready by his first wife Ælfgifu, and was the heir apparent to the kingdom until his death. He is first mentioned as a witness to a charter of his father in 993. He probably spent part of his childhood at Æthelingadene, Dean in west Sussex, and his paternal grandmother Ælfthryth may have played an important part in his upbringing. Almost nothing is known of his life, although he seems to have formed a friendship with Sigeforth and Morcar, two of the leading thegns of the Five Boroughs of the East Midlands.

In December 1013 the Danish king Sweyn conquered England and King Æthelred was forced into exile in Normandy, but he returned following Sweyn's death in February 1014. It is not known what became of Æthelstan and his surviving full brothers, Edmund Ironside and Eadwig, during Sweyn's rule, but they probably remained somewhere in England. Æthelstan's last mention in a charter is in one dated 1013.