Charles I, Landgrave of Hesse-Kassel
Charles of Hesse- Kassel( 3 August 1654 – 23 March 1730), of the House of Hesse, was the Landgrave of Hesse- Kassel from 1670 to 1730.
Princess Marie Luise Charlotte of Hesse-Kassel
Princess Marie Luise Charlotte of Hesse- Kassel,( 9 May 1814 – 28 July 1895) was a member of the House of Hesse- Kassel by birth.
Through her marriage to Prince Frederick Augustus of Anhalt- Dessau, she became a princess of Anhalt- Dessau.
Prince William of Hesse-Kassel
Prince William of Hesse- Kassel( 24 December 1787 – 5 September 1867), was the first son of Prince Frederick of Hesse- Kassel and Princess Caroline of Nassau- Usingen.
Margravine Hedwig Sophie of Brandenburg
Hedwig Sophia of Brandenburg( 14 July 1623, Berlin- 26 June 1683, Schmalkalden) was Landgravine consort of Hesse- Kassel by marriage to William VI, Landgrave of Hesse- Kassel, and regent from 1663 until 1677 during the minority of her sons, William VII, Landgrave of Hesse- Kassel and Charles I, Landgrave of Hesse- Kassel.
William VII, Landgrave of Hesse-Kassel
William VII of Hesse- Kassel( 21 June 1651 – 21 November 1670) was Landgrave of Hesse- Kassel.
Sophie Charlotte of Hesse-Kassel
Sophie Charlotte of Hesse- Kassel( 16 July 1678, Kassel – 30 May 1749, Bützow) was a princess of Hesse- Kassel and by marriage Duchess of Mecklenburg.
George Charles of Hesse-Kassel
George Charles of Hesse-Kassel (8 January 1691 – 5 March 1755) was a prince of Hesse-Kassel and a Prussian General.
Charles I Louis, Elector Palatine
Charles Louis, , Elector Palatine KG (22 December 1617 – 28 August 1680) was the second son of Frederick V of the Palatinate, the "Winter King" of Bohemia, and of Elizabeth Stuart, Queen of Bohemia and sister of Charles I of England.
After living the first half of his life in exile during the German Thirty Years' War and the English Civil War, in 1649 Charles Louis reclaimed his father's title of Elector Palatine along with most of his former territories.
Landgravine Charlotte of Hesse-Kassel
Charlotte of Hesse-Kassel (20 November 1627 – 26 March 1686) was the consort of Charles I Louis, Elector Palatine and mother of Elizabeth Charlotte of the Palatinate.
Princess Charlotte of Denmark
Princess Louise Charlotte of Denmark( 30 October 1789 – 28 March 1864) was a Danish princess, and a princess of Hesse- Kassel by marriage to Prince William of Hesse- Kassel.
She played an important role in the succession crisis in Denmark in the first half of the 19th century.

Question: Who is the father-in-law of Landgravine Charlotte Of Hesse-Kassel?
Answer: Frederick V