Cynethryth
Cynethryth(" Cyneðryð"; died after AD 798) was a Queen of Mercia, wife of King Offa of Mercia and mother of King Ecgfrith of Mercia.
Cynethryth is the only Anglo- Saxon Queen consort in whose name coinage was definitely issued.
John Vernou Bouvier III
John Vernou" Black Jack" Bouvier III( May 19, 1891 – August 3, 1957) was an American Wall Street stockbroker and socialite.
He was the father of First Lady Jacqueline Kennedy Onassis and of socialite Lee Radziwill, and was the father- in- law of John F. Kennedy.
Ogawa Mataji
Viscount was a general in the early Imperial Japanese Army.
He was also the father- in- law of Field Marshal Gen Sugiyama.
Ælfflæd of Mercia
Ælfflæd was a daughter of Offa of Mercia and Cynethryth.
She may have witnessed a charter with her father, mother, and brother Ecgfrith in the 770s.
She certainly witnessed a charter in 787 with her mother, father, brother, and two sisters; here she is described as "virgo"—unmarried.
It is possible that she was the daughter of Offa
whose proposed marriage to Charles the Younger caused a dispute between Charlemagne and Offa in around 789–790.
In 792 she married Æthelred I of Northumbria at Catterick.
Here she is described as "queen", which has suggested to some historians that she had been previously married, and to a king, perhaps to one of Æthelred's predecessors.
Peter Burroughs
Peter Burroughs( born 27 January 1947) is a British television and film actor, the director of Willow Management.
He is the father- in- law of actor and TV presenter Warwick Davis.
Æthelred I of Northumbria
Æthelred (c. 762 – 18 April 796), was the king of Northumbria from 774 to 779 and again from 790 until he was murdered in 796.
He was the son of Æthelwald Moll and Æthelthryth and possibly became king while still a child after Alhred was deposed.
Ludwig von Westphalen
Johann Ludwig von Westphalen( 11 July 1770 – 3 March 1842) was a liberal Prussian civil servant and the father- in- law of Karl Marx.
John Adams (merchant)
John Adams( 1672 or 1673 – 1745) was an American- born Canadian merchant and member of the Nova Scotia Council.
He was the father- in- law of Henry Newton( politician).
James Armour (Master mason)
James Armour (15 January 1730 – 20 September 1798) was a master mason and father of Jean Armour, and therefore the father-in-law of the poet Robert Burns.
Barthold A. Butenschøn Sr.
Hans Barthold Andresen Butenschøn( 27 December 1877 – 28 November 1971) was a Norwegian businessperson.
He was born in Kristiania as a son of Nils August Andresen Butenschøn and Hanna Butenschøn, and grandson of Nicolay Andresen.
Together with Mabel Anette Plahte( 1877 – 1973, a daughter of Frithjof M. Plahte) he had the son Hans Barthold Andresen Butenschøn Jr. and was through him the father- in- law of Ragnhild Butenschøn and grandfather of Peter Butenschøn.
Through his daughter Marie Claudine he was the father- in- law of Joakim Lehmkuhl, through his daughter Mabel Anette he was the father- in- law of Harald Astrup( a son of Sigurd Astrup) and through his daughter Nini Augusta he was the father- in- law of Ernst Torp.
He took commerce school and agricultural school.
He was hired in the family company N. A. Andresen& Co, and became a co-owner in 1910.
He eventually became chief executive officer.
The bank changed its name to Andresens Bank in 1913 and merged with Bergens Kreditbank in 1920.
The merger was dissolved later in the 1920s.
He was also a landowner, owning Nedre Skøyen farm and a lot of land in Enebakk.
He chaired the board of Nydalens Compagnie from 1926, having not been a board member before that.
He also chaired the supervisory council of Forsikringsselskapet Viking and Nedre Glommen salgsforening, and was a supervisory council member of Filharmonisk Selskap.
He was a member of the gentlemen's club SK Fram since 1890, and was proclaimed a lifetime member in 1964.
He was buried in Enebakk.

Question: Who is Ælfflæd Of Mercia's father-in-law?
Answer: Æthelwald Moll