Charlotte of Bourbon
Charlotte of Bourbon (1546/1547 – 5 May 1582) was a Princess consort of Orange as the third spouse of William the Silent, Prince of Orange, the main leader of the Dutch revolt against the Spanish.
She was the fourth daughter of Louis, Duke of Montpensier and Jacqueline de Longwy, Countess of Bar-sur-Seine.
Frederick Augustus, Duke of Nassau
Friedrich August, Duke of Nassau, Prince of Nassau- Usingen( 23 April 1738 in Usingen – 24 March 1816 in Wiesbaden) was the last Prince of Nassau- Usingen and, jointly with his cousin, Friedrich Wilhelm of Nassau- Weilburg, first Duke of Nassau.
He died without surviving male issue and was succeeded by his cousin's son, Wilhelm.
Frederick William, Prince of Nassau-Weilburg
Frederick William, Prince of Nassau- Weilburg( 25 October 1768, The Hague – 9 January 1816, Weilburg) was a ruler of Nassau- Weilburg.
In 1806 he was given the title of Prince of Nassau, while his cousin, Prince Frederick Augustus of Nassau- Usingen, became the Duke of Nassau.
Frederick William died in January 1816, only two months before his cousin.
Both men were succeeded by Frederick William's son, William.
Henry I, Count of Nassau-Siegen
Henry I of Nassau- Siegen,( – between 13 July and 14 August 1343) was Count of Nassau- Siegen, a part of the County of Nassau, and ancestor of the House of Nassau- Siegen.
He comes from the Ottonian branch of the House of Nassau.
Elisabeth of Nassau-Dillenburg, Countess of Wied
Elisabeth of Nassau-Dillenburg (1 December 1488 – 3 June 1559 in Dillenburg) was a member of the House of Nassau.
She was a daughter of John V of Nassau-Dillenburg and his wife Elisabeth of Hesse-Marburg.
Her brothers were Henry III of Nassau-Breda, John of Nassau-Vianden-Dietz, Ernest of Nassau and William the Rich.
Her sister was Maria of Nassau.
Otto I, Count of Nassau
Otto I of Nassau,( † between 3 May 1289 and 19 March 1290) was Count of Nassau and is the ancestor of the Ottonian branch of the House of Nassau.
Countess Charlotte Flandrina of Nassau
Countess Charlotte Flandrina of Nassau( Antwerp, 18 August
1579 – St. Croix( near Poitiers), 16 April 1640) was the fourth daughter of William the Silent and his third spouse Charlotte of Bourbon.
Countess Charlotte Brabantina of Nassau
Countess Charlotte Brabantina of Nassau
(Antwerp, 17 September 1580 – Château-Renard, August 1631) was the fifth daughter of William the Silent and his third spouse, Charlotte of Bourbon.
Henri de La Trémoille
Henri de La Trémoille( 22 December 1598 – 21 January 1674) was the 3rd Duke of Thouars, 2nd Duke of La Tremoille, and Prince of Talmond and Taranto.
He was the son of Claude de La Trémoille and his wife, Charlotte Brabantina of Nassau, and a descendant of the medieval general Louis de La Trémoille.
Walram II, Count of Nassau
Walram II of Nassau,( – 24 January 1276), was Count of Nassau and is the ancestor of the Walramian branch of the House of Nassau.

Question: Who is Countess Charlotte Brabantina Of Nassau's maternal grandfather?
Answer: Louis, Duke of Montpensier