Ulrich, Duke of Mecklenburg
Ulrich III, Duke of Mecklenburg or Ulrich III of Mecklenburg- Güstrow( 5 March 1527 – 14 March 1603) was Duke of Mecklenburg( Güstrow) from 1555- 56 to 1603.
Henry I of Werle
Henry I( died 8 October 1291) was a Prince of Mecklenburg- Werle and Mecklenburg- Güstrow.
John Albert II, Duke of Mecklenburg
John Albert II, Duke of Mecklenburg[ Güstrow]
( 5 May 1590 in Waren – 23 April 1636 in Güstrow) was a Duke of Mecklenburg.
From 1608 to 1611, he was the nominal ruler of Mecklenburg- Schwerin; the actual ruler being the regent, his great- uncle Charles I. From 1611 to 1621 John Albert and his brother Adolf Frederick I jointly ruled the whole Duchy of Mecklenburg.
From 1621, John Albert ruled Mecklenburg- Güstrow alone.
Frederick IV of Denmark
Frederick IV (11 October 1671 – 12 October 1730) was the king of Denmark and Norway from 1699 until his death.
Frederick was the son of King Christian V of Denmark-Norway and his consort Charlotte Amalie of Hesse-Kassel.
Charles of Mecklenburg-Güstrow
Charles, Duke of Mecklenburg- Güstrow( 18 November 1664 in Güstrow – 15 March 1688 in Güstrow) was the hereditary prince of Mecklenburg- Güstrow.
He was a son of Gustavus Adolph and his wife Magdalene Sibylle née Duchess of Schleswig- Holstein- Gottorp, a daughter of Frederick III.
Hedwig of Mecklenburg-Güstrow
Hedwig of Mecklenburg- Güstrow(" Hedwig Eleonore"; 12 January 1666 – 9 August 1735), was a German noblewoman member of the House of Mecklenburg and by marriage Duchess of Saxe- Merseburg- Zörbig.
Born in Güstrow, she was the eighth of eleven children born from the marriage of Gustav Adolph, Duke of Mecklenburg- Güstrow and Magdalene Sibylle of Holstein- Gottorp.
From her ten older and younger siblings, eight survive adulthood: Marie( by marriage Duchess of Mecklenburg- Strelitz), Magdalene, Sophie( by marriage Duchess of Württemberg- Oels), Christine( by marriage Countess of Stolberg- Gedern), Charles, Hereditary Prince of Mecklenburg- Güstrow, Louise( by marriage Queen of Denmark and Norway), Elisabeth( by marriage Duchess of Saxe- Merseburg- Spremberg) and Augusta.
Gustav Adolph, Duke of Mecklenburg-Güstrow
Gustav Adolph, Duke of Mecklenburg [Güstrow] (26 February 1633 – 6 October 1695) was the last ruler of Mecklenburg-Güstrow from 1636 until his death and last Lutheran Administrator of the Prince-Bishopric of Ratzeburg from 1636 to 1648.
Louise of Mecklenburg-Güstrow
Louise of Mecklenburg-Güstrow (28 August 1667 – 15 March 1721) was Queen consort of Denmark and Norway as the first spouse of the King Frederick IV of Denmark.
In 1708–09, she was regent during her husband's trip to Italy.
Christine of Mecklenburg-Güstrow
Christine of Mecklenburg- Güstrow( 14 August 1663 – 3 August 1749) was a German noblewoman of the House of Mecklenburg and by marriage Countess of Stolberg- Gedern.
Born in Güstrow, she was the sixth of eleven children born from the marriage of Gustav Adolph, Duke of Mecklenburg- Güstrow and Magdalene Sibylle of Holstein- Gottorp.
From her ten older and younger siblings, eight survived to adulthood: Marie( by marriage Duchess of Mecklenburg- Strelitz), Magdalene, Sophie( by marriage Duchess of Württemberg- Oels), Charles, Hereditary Prince of Mecklenburg- Güstrow, Hedwig( by marriage Duchess of Saxe- Merseburg- Zörbig), Louise( by marriage Queen of Denmark and Norway), Elisabeth( by marriage Duchess of Saxe- Merseburg- Spremberg) and Augusta.
She was the three- times great- grandmother of Queen Victoria of the United Kingdom.
Princess Charlotte Amalie of Denmark
Princess Charlotte Amalie of Denmark and Norway (6 October 1706 – 28 October 1782) was a Danish princess, daughter of King Frederick IV of Denmark and Louise of Mecklenburg-Güstrow.

Question: Who is the father-in-law of Louise Of Mecklenburg-Güstrow?
Answer: Christian V of Denmark