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.
Valdemar the Young
Valdemar the Young  (– 28 November 1231) was King of Denmark from 1218 until his death.
Valdemar was the eldest son and co-ruler of King Valdemar II of Denmark by his first wife, Dagmar of Bohemia.
He did not outlive his father
so was never a sole monarch.
He is sometimes referred to as Valdemar III for example his tombstone reads in "Valdemar the Third, King of Denmark, son of Valdemar the Second".
Although Valdemar III is more commonly used to denote a later king, Valdemar of Schleswig.
Dagmar of Bohemia
Dagmar of Bohemia (also known as Margaret, ; 1186 – 24 May 1212 in Ribe) was Queen of Denmark as the first spouse of King Valdemar II.
She was the daughter of King Ottokar I of Bohemia and his first wife, Adelaide of Meissen.
Guillaume Wittouck
Guillaume Wittouck( 1749- 1829) was a Belgian lawyer and High Magistrate.
He was the Grandfather of industrialist Paul Wittouck.
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).
Valdemar II of Denmark
Valdemar II( 9 May 117028 March 1241), called Valdemar the Victorious or Valdemar the Conqueror(" Valdemar Sejr"), was the King of Denmark from 1202 until his death in 1241.
The nickname" Sejr" is a later invention and was not used during the King's own lifetime.
" Sejr" means" victory" in Danish.
Abd al-Muttalib
Abd al- Muttalib Shaybah ibn Hashim( c. 497 – 578) was the grandfather of Islamic prophet Muhammad.
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.
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.

Question: Who is the maternal grandfather of Valdemar The Young?
Answer: Ottokar I of Bohemia