Guillaume Wittouck
Guillaume Wittouck( 1749- 1829) was a Belgian lawyer and High Magistrate.
He was the Grandfather of industrialist Paul Wittouck.
Prithvipati Shah
Prithvipati Shah( ?–1716) was the king of the Gorkha Kingdom in the Indian subcontinent, present- day Nepal.
He was the grandfather of Nara Bhupal Shah.
Duke Franz Joseph in Bavaria
Duke Franz Joseph in Bavaria, full German name:" Franz Joseph Michael Karl
Maria Evaristus Quirinus Ottokar Herzog in Bayern"( 23 March 1888, Schloss Tegernsee, Kingdom of Bavaria – 23 September 1912, Munich, Kingdom of Bavaria) was a Duke in Bavaria and member of the House of Wittelsbach.
Franz Joseph was the fifth and youngest child of Duke Karl- Theodor in Bavaria and his wife Infanta Maria Josepha of Portugal.
Franz Joseph was the brother of Duke Ludwig Wilhelm in Bavaria and sisters Duchess Amalie in Bavaria, Duchess Sophie Adelheid in Bavaria, Duchess Elisabeth in Bavaria and Duchess Marie Gabrielle in Bavaria.
Kaya Alp
Kaya Alp was, according to Ottoman tradition, the son of Kızıl Buğa and the father of Suleyman Shah, who was, in turn, the grandfather of Ertuğrul, and the great grandfather of the Ottoman Empire founder, Osman I.
Abd al-Muttalib
Abd al- Muttalib Shaybah ibn Hashim( c. 497 – 578) was the grandfather of Islamic prophet Muhammad.
Duke Pius August in Bavaria
Duke" Pius August" in Bavaria, full German name:" Pius August Herzog in Bayern"( born 1 August 1786 in Landshut, Electorate of Bavaria; died 3 August 1837 in Bayreuth, Kingdom of Bavaria) was a Duke in Bavaria as a member of the Palatine Birkenfeld- Gelnhausen line of the House of Wittelsbach.
Pius
August was a grandfather of Empress Elisabeth of Austria through his son Duke Maximilian Joseph in Bavaria, as well as a great grandfather of Queen Elisabeth of the Belgians and an ancestor of the current generations of the Belgian and Italian Royal Families and the Grand Ducal Family of Luxembourg.
Duke Siegfried August in Bavaria
Duke Siegfried in Bavaria, full German name: "
Siegfried August Maximilian Maria, Herzog in Bayern"
(10 July 1876,
Bamberg, Kingdom of Bavaria – 12 March 1952, Munich, Republik of Bavaria) was a Duke in Bavaria and member of the House of Wittelsbach.
Siegfried August was the first of three sons of Duke Maximilian Emanuel in Bavaria and his wife Princess Amalie of Saxe-Coburg and Gotha.
Siegfried August was the brother of "Christoph" Joseph Clemens Maria, Duke in Bavaria and "Luitpold" Emanuel Ludwig Maria, Duke in Bavaria.
Princess Amalie of Saxe-Coburg and Gotha
Princess Amalie of Saxe-Coburg and Gotha (Marie Luise Franziska Amalie; 23 October 1848 – 6 May 1894) was a Princess of Saxe-Coburg and Gotha by birth and a Duchess in Bavaria through her marriage to Duke Maximilian Emanuel in Bavaria.
Amalie was the fourth child and second eldest daughter of Prince August of Saxe-Coburg and Gotha and his wife Princess Clémentine of Orléans.
Her youngest brother was Ferdinand I of Bulgaria.
Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.
He was the grandfather of singer/ poet Leonard Cohen.
John Westley
Rev. John Westley( 1636 – 78) was an English nonconformist minister.
He was the grandfather of John Wesley( founder of Methodism).

Question: Who is the maternal grandfather of Duke Siegfried August In Bavaria?
Answer: Prince August of Saxe-Coburg and Gotha