Princess Caroline-Mathilde of Denmark
Princess Caroline- Mathilde of Denmark( 27 April 1912 – 12 December 1995) was a daughter of Prince Harald of Denmark and granddaughter of King Frederick VIII of Denmark.
As the wife of Knud, Hereditary Prince of Denmark, she became Hereditary Princess of Denmark.
Kaoru Hatoyama
After the elections of 2009, she became more widely known as the grandmother of Prime Minister Yukio Hatoyama and his politician brother Kunio Hatoyama.
Isabella of Austria
Isabella of Austria (18 July 1501 – 19 January 1526), also known as Elizabeth, Archduchess of Austria and Infanta of Castile and Aragon, was Queen of Denmark, Sweden and Norway as the wife of King Christian II.
She was the daughter of King Philip I and Queen Joanna of Castile and the sister of
Emperor Charles V. She was born at Brussels.
She served as regent of Denmark in 1520.
Christina of Saxony
Christina of Saxony( b. Torgau, 25 December 1461 – d. Odense, 8 December 1521), was Queen consort of Denmark, Norway, and Sweden.
She was born a granddaughter of Frederick the Gentle of Saxony, and daughter of Ernest, Elector of Saxony and Elisabeth of Bavaria.
She was the grandmother of Christina of Denmark through her son Christian II.
Anne Denman
Anne Denman( 1587–1661) was born in Olde Hall, Retford, Nottinghamshire.
Through a fortunate second marriage with Thomas Aylesbury, she became the grandmother of Lady Anne Hyde, Duchess of York and great- grandmother of Queen Mary II and Queen Anne.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.
Hubba bint Hulail
Hubba bint Hulail was the grandmother of Hashim ibn' Abd Manaf, thus the great- great- great- grandmother of the Islamic" Nabī"( Prophet) Muhammad ibn Abdullah.
Christina of Denmark
Christina of Denmark (November 1521 – 10 December 1590) was a Danish princess, the younger surviving daughter of King Christian II of Denmark and Norway and Isabella of Austria.
She became the duchess-consort of Milan, then duchess-consort of Lorraine.
She served as the regent of Lorraine from 1545 to 1552 during the minority of her son.
She was also a claimant to the thrones of Denmark, Norway and Sweden in 1561-1590.
Finally, she was sovereign Lady of Tortona in 1578-1584.
Tjuyu
Tjuyu( sometimes transliterated as Thuya or Thuyu) was an Egyptian noblewoman and the mother of queen Tiye, and the wife of Yuya.
She is the grandmother of Akhenaten, and great grandmother of Tutankhamun.
Francis of Denmark
Francis of Denmark( 15 July 1497 – 1 April 1511), was a prince of Denmark, Norway and Sweden, the youngest son of King John of Denmark and Christina of Saxony.

Question: Who is Christina Of Denmark's maternal grandmother?
Answer: Joanna