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.
Gian Maria Visconti
Gian Maria Visconti( or Giovanni Maria; 7 September 1388 in Abbiategrasso – 16 May 1412) was the second Visconti Duke of Milan, the son of Gian Galeazzo Visconti and Caterina Visconti.
Estorre Visconti
Estorre Visconti, or Astorre according to other sources( 13467 January 1413), was one of the many illegitimate sons of the famous Bernabò Visconti, Lord of Milan and already deposed by his nephew Gian Galeazzo Visconti in 1385.
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.
Gian Galeazzo Visconti
Gian Galeazzo Visconti (16 October 1351 – 3 September 1402), son of Galeazzo II Visconti and Bianca of Savoy, was the first Duke of Milan (1395) and ruled the late-medieval city just before the dawn of the Renaissance.
He was the founding patron of the Certosa di Pavia, completing the Visconti Castle at Pavia begun by his father and furthering work on the Duomo of Milan.
John III, Count of Armagnac
John III of Armagnac (1359 – July 25, 1391) was a Count of Armagnac, of Fézensac and Rodez from 1384 to 1391.
He was the son of John II of Armagnac, and Jeanne of Périgord.
In 1390, John claimed the kingdom of Majorca, but was overcome by the troops of Juan I of Aragon in a battle near Navata.
John III consequently led military actions in Roussillon.
In 1391, he had to leave for Italy in order to go to the assistance of Charles Visconti, Lord of Parma and husband of his sister, Beatrix of Armagnac.
Visconti was in conflict with his acquisitive cousin Gian Galeazzo Visconti, later the duke of Milan, whose ambition was to control the whole of northern Italy.
His army was attacked and decisively beaten by that of Gian Galeazzo Visconti as it passed through Alessandria in Piedmont.
John III was killed in the battle.
Isabella, Countess of Vertus
Isabella of France (1 October 1348 – 11 September 1373) was a French princess and member of the House of Valois, as well as the wife of Gian Galeazzo Visconti, who after her death became Duke of Milan.
Born in Bois de Vincennes, Isabella was the youngest daughter of King John II of France by his first wife, Bonne of Bohemia.
Her maternal uncle Count Amadeus VI of Savoy arranged her marriage with Gian Galeazzo Visconti.
As her dowry, Isabella received the county of Sommières, exchanged later for the county of Vertus.
On 8 October 1360, Isabella and Gian Galeazzo were married in Milan, and six months later, in April 1361, she was declared sovereign Countess of Vertus.
The couple had four children:
Isabella died in childbirth in Pavia in 1373.
Bianca of Savoy
Bianca of Savoy (1337– Pavia, 31 December 1387) was Lady of Milan by marriage to Galeazzo II Visconti.
She was the only surviving daughter of Aimone, Count of Savoy and Yolande Palaeologina of Montferrat.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.
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.

Question: Who is the maternal grandmother of Gian Galeazzo Visconti?
Answer: Yolande Palaeologina of Montferrat