Karl Franz Lodron
Count Karl Franz von Lodron( 1791 –1828) was the last Prince- Bishop of Brixen.
Princess Marie-Auguste of Anhalt
Princess Marie Auguste of Anhalt (10 June 1898 – 22 May 1983) was the daughter of Eduard, Duke of Anhalt, and his wife, Princess Louise Charlotte of Saxe-Altenburg.
She married and divorced a son of Kaiser Wilhelm II, then married and divorced a baron.
Princess Elisabeth of Prussia
Princess Elisabeth of Prussia( 18 June 1815 – 21 March 1885) was the second daughter of Prince Wilhelm of Prussia and Landgravine Marie Anna of Hesse- Homburg and a granddaughter of Frederick William II of Prussia.
Prince Philip, Duke of Edinburgh is her great- great- grandson.
Princess Marie of Prussia (1855–1888)
Princess Marie of Prussia(" Marie Elisabeth Louise Frederika"; 14 September 1855, Marmorpalais, Potsdam – 20 June 1888, Dresden), was a princess of the House of Hohenzollern.
She was the daughter of Prince Frederick Charles of Prussia and later became second wife of Prince Henry of the Netherlands then the first wife of Prince Albert of Saxe- Altenburg.
She was also the great- niece of Wilhelm I, German Emperor.
Prince Karl Franz of Prussia
Prince Karl Franz of Prussia (15 December 1916 – 23 January 1975) was the only child of Prince Joachim of Prussia and his wife Princess Marie-Auguste of Anhalt.
He was also the grandson of Wilhelm II, German Emperor, himself a grandson of Queen Victoria, which made Prince Karl a great-great-grandson of the British queen.
Princess Charlotte of Prussia (1831–1855)
Princess Charlotte of Prussia( 21 June 1831 – 30 March 1855), was by birth a Princess of Prussia and member of the House of Hohenzollern and by marriage Hereditary Princess of Saxe- Meiningen.
She was the eldest child and daughter of Prince Albert of Prussia( younger son of Frederick William III of Prussia and Louise of Mecklenburg- Strelitz) and his first wife Princess Marianne of the Netherlands( daughter of William I of the Netherlands and Wilhelmine of Prussia).
Princess Marianne of Prussia
Princess Marianne of Prussia( 23 August 19131 March 1983) was a member of the House of Hohenzollern, daughter of Prince Friedrich Wilhelm of Prussia.
Princess Maria Elisabeth of Bavaria
Princess Maria Elisabeth of Bavaria( 9 September 1914 – 13 May 2011) was the eldest daughter of Prince Franz of Bavaria, third son of Ludwig III of Bavaria.
Prince Boris of Leiningen
Prince Karl" Boris" Frank Markwart of Leiningen( born 17 April 1960) is the elder son of Prince Karl of Leiningen and of his wife, Princess Marie Louise of Bulgaria.
As a third great- grandson of Queen Victoria, he is in the line of succession to the throne of Canada and those of the other Commonwealth realms.
Princess Calixta of Lippe
Princess "Calixta" Agnes Adelaide Irmgard Helene Caroline Elise Emma of Lippe (14 October 1895 - 15 December 1982) was the wife of Prince Waldemar of Prussia, eldest son of Prince Henry of Prussia.

Question: Who is Prince Karl Franz Of Prussia's maternal grandfather?
Answer: Eduard