Maximilian I, Prince of Hohenzollern-Sigmaringen
Maximilian I, Prince of Hohenzollern- Sigmaringen( 20 January 1636 – 13 August 1689 in Sigmaringen) was a German nobleman.
He was the third ruling Prince of Hohenzollern- Sigmaringen; he ruled from 1681 until his death.
Princess Amalie of Hohenzollern-Sigmaringen
Princess" Amalie" Antoinette Karoline Adrienne of Hohenzollern- Sigmaringen( 30 April 1815, Sigmaringen, Principality of Hohenzollern- Sigmaringen – 14 January 1841, Sigmaringen, Principality of Hohenzollern- Sigmaringen) was a member of the House of Hohenzollern- Sigmaringen and a Princess of Hohenzollern- Sigmaringen by birth.
Through her marriage to Prince Eduard of Saxe- Altenburg, Amalie was also a member of the House of Saxe- Altenburg and Princess of Saxe- Altenburg.
Amalie was a grand- niece of Joachim Murat, King of the Two Sicilies from 1808 to 1815 and a brother- in- law of Napoleon Bonaparte, through marriage to Napoleon's youngest sister, Caroline Bonaparte.
Charles II, Count of Hohenzollern-Sigmaringen
Charles II, Count of Hohenzollern-Sigmaringen "(German: Karl II, Graf von Hohenzollern-Sigmaringen)" (1547 – 8 April 1606) became Count of Hohenzollern-Sigmaringen in 1576 and remained so until his death.
He was the fifth but second surviving son of Charles I, Count of Hohenzollern and Anna, daughter of Ernest, Margrave of Baden-Durlach.
Johann, Prince of Hohenzollern-Sigmaringen
Prince Johann of Hohenzollern- Sigmaringen( 17 August 1578 in Sigmaringen – 22 March 1638 in Munich), was the ruling Count of Hohenzollern- Sigmaringen from 1606 to 1623.
He was elevated to the rank of prince in 1623 and so was" Prince" of Hohenzollern- Sigmaringen from 1623 until his death.
Prince Karl Anton of Hohenzollern
Prince Karl Anton of Hohenzollern- Sigmaringen( 1 September 1868 – 21 February 1919) was a member of the Princely House of Hohenzollern- Sigmaringen.
Karl Anton was the third and youngest son of Leopold, Prince of Hohenzollern and his wife Infanta Antónia of Portugal.
Karl Anton's elder brothers were William, Prince of Hohenzollern and Ferdinand I of Romania.
Meinrad I, Prince of Hohenzollern-Sigmaringen
Meinrad I of Hohenzollern- Sigmaringen( 1605 in Munich – 30 January 1681 in Sigmaringen) was Prince of Hohenzollern- Sigmaringen from 1638 until his death.
Marie Antoinette Murat
Marie Antoinette Murat,( 3 January 1793, Labastide- Murat, Lot, French Republic – 19 January 1847, Sigmaringen, Principality of Hohenzollern- Sigmaringen) was a member of the House of Murat.
Through her marriage to Charles, Prince of Hohenzollern- Sigmaringen, Marie Antoinette was also a member of the House of Hohenzollern- Sigmaringen and Princess consort of Hohenzollern- Sigmaringen.
Marie Antoinette was the niece of Joachim Murat, King of Naples from 1808 to 1815 and a brother- in- law of Napoleon Bonaparte, through marriage to Napoleon's youngest sister, Caroline Bonaparte.
Karl Anton, Prince of Hohenzollern
Prince Karl Anton of Hohenzollern- Sigmaringen( 7 September 1811 – 2 June 1885) was head of the Princely House of Hohenzollern- Sigmaringen, Hohenzollern from 1869 and Prime Minister of Prussia.
He was the son of Karl, Prince of Hohenzollern- Sigmaringen, who abdicated in favour of his son on 27 August 1848, and his first wife Marie Antoinette Murat, niece of Joachim Murat.
Prince Frederick of Hohenzollern-Sigmaringen
Prince Frederick of Hohenzollern-Sigmaringen  (25 June 1843, Schloss Inzigkofen, Inzigkofen, Hohenzollern-Sigmaringen – 2 December 1904, Munich, Kingdom of Bavaria) was a member of the House of Hohenzollern-Sigmaringen and a Prussian General of the Cavalry.
Frederick was the fifth child and youngest son of Charles Anthony, Prince of Hohenzollern and his wife Princess Josephine of Baden.
Princess Josephine of Baden
Princess Josephine Friederike Luise of Baden (21 October 1813 – 19 June 1900) was born at Mannheim, the second daughter of Charles, Grand Duke of Baden and his wife, Stéphanie de Beauharnais.
Through her son, Carol I, she is the ancestress of the Romanian royal family and the Yugoslav Royal family.
Through her younger daughter Marie, she is also the ancestress of the Belgian royal family and the Grand Ducal family of Luxembourg.

Question: Who is the maternal grandfather of Prince Frederick Of Hohenzollern-Sigmaringen?
Answer: Charles, Grand Duke of Baden