Juana de Castro
Juana de Castro (died 21 August 1374) was queen of Castile, as wife of King Peter of Castile and sister of Inês de Castro.
She was the daughter of Pedro Fernández de Castro and Isabel Ponce de Leon.
She married King Peter in 1354.
Her tomb is in the Santiago de Compostela Cathedral.
João of Braganza, Marquis of Montemor-o-Novo
João of Braganza, born ca. 1430, was the second son of Fernando I, Duke of Braganza and of his wife, the duchess Joan of Castro.
Lionel Royer
Lionel- Noël Royer( December 25, 1852 – 30 June 1926) was a French painter.
He was most famous for painting large scenes of the life of Joan of Arc in the in Domrémy.
Jean Pasquerel
Jean Pasquerel( c. 1400) was an Augustinian friar( member of the Order of St. Augustine), almoner and confessor of Joan of Arc.
Jean de Metz
Jean de Metz( also Jean de Nouillonpont)( born c. 1398) was a French nobleman who is known primarily for his role in the exploits of Joan of Arc.
Robert le Maçon
Robert le Maçon( c. 1365 – 28 January 1443) was chancellor of France, advisor to Charles VII and supporter of Joan of Arc.
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.
Fred Le Deux
Frederick" Fred" Le Deux( born 4 December 1934) was an Australian rules footballer who played with Geelong in the Victorian Football League( VFL).
He is the grandfather of Tom Hawkins.
Henry Krause
Henry J." Red" Krause, Jr.( August 28, 1913 – February 20, 1987) was an American football offensive lineman in the National Football League for the Brooklyn Dodgers and the Washington Redskins.
He played college football at St. Louis University.
He is the grandfather of Jennifer Krause
He is the great grandfather of Payton Hoeing
Isabel Ponce de León
Isabel Ponce de León (died 1367) was a Spanish noblewoman from the Ponce de Leon family.
Her father was Pedro Ponce de León (Adelantado), lord of Cangas and Tineo, and her mother was Sancha Gil de Chacim.
She was the lady of Villanueva de los Infantes, Castrelo, and Espinosa.
She was a great-great-granddaughter of King Alfonso IX of León, and Pedro Ponce de Cabrera.

Question: Who is Juana De Castro's maternal grandfather?
Answer: Pedro Ponce de León (Adelantado)