Diana Guardato
Diana Guardato was a member of the aristocratic Patrician Guardato family, and had three children with King Ferdinand I: Diana Guardato is the 16th- Great Grandmother of His Royal Highness Albert II of Belgium, 15th- Great Grandmother of His Majesty Juan Carlos
I of Spain, 17th- Great Grandmother of Philippe of Belgium, 14th- Great Grandmother of His Majesty Manuel II of Portugal, 16th- Great Grandmother of Grand Duke Henri, as well as many others.
Alfonso III d'Este, Duke of Modena
Alfonso III d' Este( 22 October 1591 – 26 May 1644) was Duke of Modena and Reggio from 1628 to 1629.
He was the husband of Princess Isabella of Savoy, daughter of Charles Emmanuel I, Duke of Savoy and his wife Infanta Catherine Michelle of Spain.
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.
Mona Hopton Bell
Mona Hopton Bell( 1867- 1940) was a British artist, best known for her portraits of civic figures.
She was the grandmother of the painter Jean H. Bell.
Isabella of Savoy
Isabella of Savoy (11 March 1591 – 28 August 1626) was a daughter of Charles Emmanuel I, Duke of Savoy, and Catherine Michelle of Spain.
Her maternal grandparents were Philip II of Spain and Elisabeth of Valois, her paternal grandparents were Emmanuel Philibert, Duke of Savoy and Margaret of France, Duchess of Berry.
She was the Hereditary Princess of Modena, dying before her husband succeeded to the Duchy of Modena in 1628.
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.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.
Elisabeth of Valois
Elisabeth of Valois  (2 April 1545 – 3 October 1568) was a Spanish queen consort as the third spouse of Philip II of Spain.
She was the eldest daughter of Henry II of France and Catherine de' Medici.
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.
Infanta Catherine Michelle of Spain
Catherine Michelle of Spain (10 October 1567 – 6 November 1597) was a Duchess consort of Savoy who served as Regent of Savoy several times during the absence of her spouse, Charles Emmanuel
I, Duke of Savoy.
As the youngest surviving daughter of Philip II of Spain and Elisabeth of Valois, she was the sister of Isabella Clara Eugenia, Governor of the Habsburg Netherlands.

Question: Who is the maternal grandmother of Infanta Catherine Michelle Of Spain?
Answer: Catherine de' Medici