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).
Catherine of Bulgaria
Catherine of Bulgaria( Bulgar: Екатерина," Ekaterina"; died after 1059) was Empress- consort to Byzantine emperor Isaac I Komnenos and co-regent of Constantine X for a period after the abdication of her spouse in 1059.
She was a daughter of Ivan Vladislav of Bulgaria and his wife Maria, and thus a sister of Presian and Alusian.
Catherine was also a paternal aunt of Maria of Bulgaria.
John Chryselios
John Chryselios was a provincial magnate in late 10th- century Dyrrhachium, and the father- in- law of Tsar Samuel of Bulgaria( r. 997–1014).
Keratsa of Bulgaria
Keratsa-Maria of Bulgaria( 1348–1390) was Princess of Bulgaria during the Second Bulgarian Empire and Empress of Byzantine Empire.
She was the daughter of Tsar Ivan Alexander of Bulgaria and his second wife, a converted Jew, Theodora.
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.
Ogawa Mataji
Viscount was a general in the early Imperial Japanese Army.
He was also the father- in- law of Field Marshal Gen Sugiyama.
Henry of Flanders
Henry (1176? – 11 June 1216) was the second emperor of the Latin Empire of Constantinople.
He was a younger son of Baldwin V, Count of Hainaut (later Baldwin VIII, count of Flanders), and Margaret I of Flanders, sister of Philip of Alsace, count of Flanders.
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.
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.
Maria of Bulgaria, Latin Empress
Maria of Bulgaria was the second Empress consort of Henry of Flanders, Latin Emperor of Constantinople.

Question: Who is the father-in-law of Maria Of Bulgaria, Latin Empress?
Answer: Baldwin V, Count of Hainaut