Thorgil Sprakling

Little is recorded about Thorgil in historical texts: most of what appears is in reference to his children, two of whom were parents of kings. Thorgil's cognomen Sprakalägg can be translated into English as "Strut-leg". In the Icelandic Knýtlinga saga he is also called "the fast". In the 11th century, English historian John of Worcester provided a pedigree for earl Beorn Estrithson that made his grandfather 'Spraclingus' a son of 'Ursius' (i.e. urso, Latin for bear or Bjørn in Danish, Björn in Swedish).

Two 13th-century writers relate folklore that derives Thorgil from the mating of a bear with a noblewoman. Danish historian Saxo Grammaticus recorded that the son born to such a union was 'named after his father' (i.e. called 'bear' - Ursius/Björn) and in turn became father of 'Thrugillus, called Sprageleg'. The Gesta Antecessorum Comitis Waldevi copies John of Worcester's pedigree but makes the Ursius, father of 'Spratlingus', an actual white bear. The 14th-century chronicle sometimes attributed to John Brompton tells a very similar tale relating to the birth of Björn, called Boresune (bear's-son), father of Siward, Earl of Northumbria, and this may represent the original form of the longer, chronologically impossible pedigree of Siward found in the Gesta that erroneously identifies Björn Boresune with Thorgil's grandson, Beorn Estrithson. It has been suggested that the role of a bear in their immediate ancestry may represent a tradition shared by relatives rather than that two independent families at about the same time both co-opted the same ancient Norwegian legend for their immediate ancestry - that Björn Boresune and Thorgil may have been brothers.

In the 18th century, Danish historian Jakob Langebek suggested this bear story was allegorical, and that the brutish 'Wild' Björn, father of Thorgil, was a reference to Jomsviking brigand leader Styrbjörn the Strong (Styrbjörn Starke), depicted by sagas as the son of Olaf Björnsson, king of Sweden. Styrbjörn's wife in the sagas is stated to have been Tyra of Denmark, the daughter of Harold Bluetooth, king of Denmark and Norway. No primary source supports this royal ancestry for Thorgil, a connection almost impossible to maintain because of the chronological inconsistencies. Thorgil is believed to have died circa 1009.

• Ulf (died 1027) - Earl in Denmark and brother-in law of King Cnut the Great. His son became King Sweyn II of Denmark.
• Eilaf (first mentioned 1009) - Earl of King Canute.
• Gytha Thorkelsdóttir - married Godwin, Earl of Wessex. mother of King Harold Godwinson of England and Edith of Wessex, Queen of King Edward the Confessor