Guillaume Wittouck
Guillaume Wittouck( 1749- 1829) was a Belgian lawyer and High Magistrate.
He was the Grandfather of industrialist Paul Wittouck.
Fujiwara no Nagara
, also known as Fujiwara no Nagayoshi, was a Japanese statesman, courtier and politician of the early Heian period.
He was the grandfather of Emperor Yōzei.
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.
Amadeus VIII, Duke of Savoy
Amadeus VIII (4 September 1383 – 7 January 1451) was a Savoyard nobleman, the son of Amadeus VII, Count of Savoy and Bonne of Berry.
He was surnamed the Peaceful.
After the death of his father in 1391, his mother acted as a regent, because of his youth.
He was an antipope of the Catholic Church from 1439 to 1449 as Felix V, in opposition to Popes Eugene IV and Nicholas V.
John Westley
Rev. John Westley( 1636 – 78) was an English nonconformist minister.
He was the grandfather of John Wesley( founder of Methodism).
Abd al-Muttalib
Abd al- Muttalib Shaybah ibn Hashim( c. 497 – 578) was the grandfather of Islamic prophet Muhammad.
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.
Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.
He was the grandfather of singer/ poet Leonard Cohen.
Bonne of Berry
Bonne of Berry (1362/1365 – 30 December 1435) was the daughter of John, Duke of Berry, and Joanna of Armagnac.
Through her father, she was a granddaughter of John II of France.
Henry Bryant (naturalist)
Henry Bryant( May 12, 1820 – February 2, 1867) was an American physician and naturalist.
He was the grandfather of Henry Bryant Bigelow.

Question: Who is Amadeus Viii, Duke Of Savoy's maternal grandfather?
Answer: John, Duke of Berry