Question:  Ælfwine Haroldsson, most probably an illegitimate son of King Harold Harefoot of England, and most likely left in his otherwise unknown mother's or grandmother's care, was the first wife of what king?
Context: Harold I ( 101617 March 1040), also known as Harold Harefoot, was King of England from 1035 to 1040.  Harold's nickname "Harefoot" is first recorded as "Harefoh" or "Harefah" in the twelfth century in the history of Ely Abbey, and according to late medieval chroniclers it meant that he was fleet of foot. Ælfgifu of Northampton ( 990 – after 1036) was the first wife of King Cnut of England and Denmark, and mother of King Harold I of England (1035–40).  She was Queen regent of Norway from 1030 to 1035. Ælfwine Haroldsson or Ælfwine was most probably an illegitimate son of King Harold Harefoot of England.  He was probably born during the early 1030s, either in Scandinavia or after 1035 in England.  He appears in an early twelfth-century cartulary from the monastery of Sainte Foi at Conques in Aquitaine as "Alboynus" (a cognate of Ælfwine), alongside the records that he was born in London and was the son of a King "Heroldus" (a Latinised version of Harold) and one "Alveva" ("Ælfgifu" Latinised).  It is also noted that he arrived in Conques in 1060 on pilgrimage and persuaded the local authorities to rebuild the church and make him prior.  W. H. Stevenson showed the only chronologically plausible candidate for his father is King Harold Harefoot.  With Harold Harefoot's sudden death on 17 March 1040 Ælfwine was most likely left in his otherwise unknown mother's care, or even that of his powerful and influential grandmother Ælfgifu of Northampton, who may be the Ælfgifu of the record mistakenly named as his mother, rather than grandmother.  He did not lay any claim to the throne of England.  Little is known about him, but he is thought to have died in the 1070s or 1080s.  He was a grandson of Cnut the Great. Admiral George Vandeput (died 14 March 1800) was an English naval officer, the illegitimate son of Sir George Vandeput, 2nd Baronet (  1717 – 17 June 1784) and an unknown mother. Christoffel van IJsselstein (died after 1510) was the illegitimate son of Frederik of Egmont, Count of Buren and Leerdam, Lord of IJsselstein (died 1521), and an unknown mother. Frederick of Pettorano ("c".  1212/3 – after 1240) was the eldest illegitimate son of Frederick II, king of Sicily and Germany.  He was born on Sicily to an Italo-Norman noblewoman after his father's first marriage to Constance of Aragon.  This mistress's name is unknown, but she came from a family of Norman counts on Sicily and had a relationship with the teenage Frederick between 1211 and 1212.  Their relationship ended when King Frederick went to Germany and in 1213 took up with another woman, a certain Adelaide.  Besides Frederick of Pettorano, Frederick II probably named two other sons after himself: another illegitimate son, Frederick of Antioch, and a legitimate son by his wife Isabella.  This last is known only by the initial "F." and died young. Sir Robert Bruce, Lord of Liddesdale (died 11 August 1332) was an illegitimate son of King Robert the Bruce and an unknown mother.  He was knighted and awarded the royal arms at the Battle of Bannockburn. Sir Roland de Velville (1471/4 - 25 June 1535, also Vielleville, Veleville, or Vieilleville) is alternatively presented as the clear "illegitimate issue" (son) of King Henry VII of England by "a Breton lady whose name is not known", or as a favored member of the court of Henry VII and later recipient of beneficences, brought home to England with 28-year-old Henry after his exile in Brittany, an adolescent "of unknown parentage", and so a possible or likely illegitimate son, with formal historical opinion undecided. Leofwine (died in or after 1023) was appointed Ealdorman of the Hwicce by King Æthelred II of England in 994.  The territory of the Hwicce was a kingdom in the western midlands in the early Anglo-Saxon period, which soon became a subdivision of Mercia.  Leofwine was the son of Ælfwine, who is otherwise unknown, but the family appears to come from the East Midlands.  Leofwine and his sons were remembered by the Worcester church as spoliators who seized church land, but as benefactors by East Midlands religious establishments. Baptised on 17 May 1762 in the church of All Saints in Chichester, he was the eldest surviving son of the Reverend William Webber (1724–1790), a canon of Chichester Cathedral.  The Canon's father, Robert Webber, was said to be an illegitimate son of Charles Lennox, 1st Duke of Richmond, himself an illegitimate son of King Charles II, while the Canon's mother was Mary Maybank, reputedly a descendant of Louise de Kérouaille, Duchess of Portsmouth, a mistress of King Charles II.  William's mother had less elevated but wholly legitimate origins, being Anne Smith (1731–1806), daughter of John Smith, a surgeon in Chichester, and his wife Sarah Buckenham.  Among his uncles were Rear-Admiral Charles Webber (1722–1783), nominal father of Lieutenant-General James Webber Smith, as well as the rector of West Stoke outside Chichester, the Reverend Charles Smith (1729–1803).  His younger brother, the Reverend James Webber (1772–1847), became Dean of Ripon.
Answer: King Cnut