George I, Prince of Waldeck and Pyrmont
George I, Prince of Waldeck and Pyrmont( 6 May 17479 September 1813) was Prince of Waldeck and Pyrmont from 1812 to 1813.
He was the son of Karl August, Prince of Waldeck and Pyrmont and Countess Palatine Christiane Henriette of Zweibrücken- Birkenfeld.
Princess Helena of Nassau
Princess Helena of Nassau (18 August 183127 October 1888) was a daughter of William, Duke of Nassau, and consort of George Victor, Prince of Waldeck and Pyrmont.
George II, Prince of Waldeck and Pyrmont
George II, Prince of Waldeck and Pyrmont( 20 September 178915 May 1845) was Prince of Waldeck and Pyrmont from 1813 to 1845.
He was the son of George I, Prince of Waldeck and Pyrmont and Countess Princess Augusta of Schwarzburg- Sondershausen.
Princess Guda of Waldeck and Pyrmont
Princess Guda of Waldeck and Pyrmont( born 22 August 1939) is the youngest daughter of Josias, Hereditary Prince of Waldeck and Pyrmont, head of the House of Waldeck and Pyrmont from 1946 to 1967 and first wife of Frederick William, Prince of Wied.
Princess Helena of Waldeck and Pyrmont (1899–1948)
Princess Helena of Waldeck and Pyrmont( 22 December 189918 February 1948) was the only daughter of Friedrich, Prince of Waldeck and Pyrmont, last reigning Prince of Waldeck and Pyrmont, and wife of Nikolaus, Hereditary Grand Duke of Oldenburg.
Wittekind, Prince of Waldeck and Pyrmont
Wittekind Adolf Heinrich Georg- Wilhelm, Prince of Waldeck and Pyrmont( born 9 March 1936) has been since 1967 the head of the House of Waldeck and Pyrmont.
Princess Helena of Waldeck and Pyrmont
Princess Helena of Waldeck and Pyrmont
(Helene Friederike Auguste; later Duchess of Albany; 17 February 1861 – 1 September 1922), who became a member of the British royal family by marriage, was the fifth daughter and child of George Victor, Prince of Waldeck and Pyrmont and his first wife, Princess Helena of Nassau.
Princess Caroline of Waldeck and Pyrmont
Caroline Louise of Waldeck and Pyrmont( 14 August 1748 – 18 August 1782), was a Princess of Waldeck and Pyrmont by birth and Duchess consort of Courland by marriage.
She was the daughter of Karl August, Prince of Waldeck and Pyrmont, and Countess Palatine Christiane Henriette of Zweibrücken- Birkenfeld.
Friedrich Anton Ulrich, Prince of Waldeck and Pyrmont
Friedrich Anton Ulrich, Prince of Waldeck and Pyrmont( 27 November 16761 January 1728) was the first reigning Prince of Waldeck and Pyrmont from 1712 to 1728.
He was the son of Christian Louis, Count of Waldeck and Countess Anna Elisabeth of Rappoltstein.
From 1706 to 1712 he was Count of Waldeck and Pyrmont.
On 6 January 1712 he was elevated to Prince by the Emperor Charles VI.
Princess Marie of Waldeck and Pyrmont
Princess Marie of Waldeck and Pyrmont (Georgine Henriette Marie; 23 May 1857 – 30 April 1882) was the third daughter of George Victor, Prince of Waldeck and Pyrmont and his wife, Princess Helena of Nassau, younger half-sister of Adolphe, Grand Duke of Luxembourg.

Question: Who is Princess Helena Of Waldeck And Pyrmont's maternal grandfather?
Answer: William, Duke of Nassau