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.
Casimir I, Duke of Cieszyn
Casimir I of Cieszyn( 1280/90 –), was Duke of Cieszyn from 1315, Duke of Siewierz from 1337 and Duke of Bytom from 1357.
He was the second son of Mieszko I, Duke of Cieszyn by his wife, probably called Grzymisława.
Wenceslaus II, Duke of Cieszyn
Wenceslaus II of Cieszyn( b. 1488/96- d. 17 November 1524), was a Duke of Cieszyn since 1518 until his death( as co-ruler of his father).
He was the second son of Casimir II, Duke of Cieszyn, by his wife Johanna, daughter of Wiktoryn of Poděbrady, Duke of Opawa.
Wenceslaus III Adam, Duke of Cieszyn
Wenceslaus III Adam of Cieszyn (December 1524 – 4 November 1579) was a Duke of Cieszyn from 1528 until his death.
He was the second but only surviving son of Wenceslaus II, co-Duke of Cieszyn, by his wife Anna, daughter of Frederick I, Margrave of Brandenburg-Ansbach.
He was born one month after his father's death, on 17 November 1524.
Duke Eugen of Württemberg (1758–1822)
Duke Eugen of Württemberg( 21 November 1758 – 20 June 1822) was a German prince.
He was the brother of Frederick I of Württemberg
Frederick of Cieszyn
Frederick of Cieszyn (b. 1480/83 - d. June 1507), was a Polish prince member of the House of Piast in the Cieszyn branch.
He was the eldest son of Casimir II, Duke of Cieszyn, by his wife Johanna, daughter of Wiktoryn of Poděbrady, Duke of Opawa.
Elizabeth Lucretia, Duchess of Cieszyn
Elizabeth Lucretia of Cieszyn; 1 June 1599 – 19 May 1653), was a reigning Duchess of Cieszyn( Teschen, Těšín) from 1625 until her death.
Born as the third child and second daughter of Adam Wenceslaus, Duke of Cieszyn( by his wife Elisabeth, daughter of Gotthard Kettler, Duke of Courland), she was the last ruler of Cieszyn from the Polish Piast dynasty.
Frederick of Denmark (bishop)
Frederick of Denmark( 13 April 1532–7 October 1556) was the youngest son of Frederick I of Denmark and Sophie of Pomerania.
He was the Prince- Bishop of Hildesheim and Bishop of Schleswig.
Casimir II, Duke of Cieszyn
Casimir II of Cieszyn  (– 13 December 1528) was a Duke of Cieszyn since 1477, ruler over Koźle during 1479–1509, since 1493 ruler over Wołów, over Pszczyna during 1498–1517, from 1506 over Opava, Duke of Głogów since 1506 (for life).
Also he was Landeshauptmann General of Silesia during 1497–1504 and 1507–1517, since 1517 until his death, Landeshauptmann over the Upper Silesia.
He was the eldest child and only son of Bolesław II, Duke of Cieszyn, by his wife Anna, daughter of Ivan Vladimirovich, Prince of Bielsk.
Frederick William, Duke of Cieszyn
Frederick William of Cieszyn (9 November 1601 – 19 August 1625) was a Duke of Cieszyn since 1617 until his death.
He was the third but only surviving son of Adam Wenceslaus, Duke of Cieszyn, by his wife Elisabeth, daughter of Gotthard Kettler, Duke of Courland.
His mother died from childbirth complications ten days after his birth, on 19 November 1602.

Question: Who is Frederick Of Cieszyn's paternal grandfather?
Answer: Bolesław II, Duke of Cieszyn