Maria Belgica of Portugal
Maria Belgica of Portugal, also known as Maria Belgica of Crato( born before 12 October 1598 – 28 July 1647), was the daughter of Manuel of Portugal, son of the self- proclaimed Portuguese king António of Crato, and Countess Emilia of Nassau( 1569 – 1629), the youngest daughter of William of Orange.
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.
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.
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.
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.
Adolf of Nassau (1540–1568)
Adolf of Nassau (Dillenburg, 11 July 1540 – Heiligerlee, 23 May 1568) was a count of Nassau, also known as Adolphus of Nassau.
He was the fourth son and sixth child of William I, Count of Nassau-Dillenburg and Juliana of Stolberg.
He was the second youngest brother of William the Silent.
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.
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 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.
Countess Catharina Belgica of Nassau
Countess Catharina Belgica of Nassau (31 July 1578 – 12 April 1648) was a countess of Hanau-Münzenberg by marriage to Philip Louis II, Count of Hanau-Münzenberg, and regent of Hanau-Münzenberg from 1612 until 1626.
She was the third daughter of William the Silent and his third spouse Charlotte of Bourbon.

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