Margaret III, Countess of Flanders
Margaret III( 13 April 1350 – 16/21 March 1405) was the last Countess of Flanders of the House of Dampierre, as well as Countess of Artois and Countess of Burgundy( as Margaret II).
She was the only surviving child and heir of Louis II, Count of Flanders( 1346 – 1384) and Margaret of Brabant.
Thierry, Count of Flanders
Theoderic (– 17 January 1168), commonly known as Thierry of Alsace, was the fifteenth count of Flanders from 1128 to 1168.
He was the youngest son of Duke Theoderic II of Lorraine and Gertrude of Flanders (daughter of Robert I of Flanders).
With a record of four campaigns in the Levant and Africa (including participation in the Second Crusade, the failed 1157–1158 siege of the Syrian city Shaizar, and the 1164 invasion of Egypt), he had a rare and distinguished record of commitment to crusading.
Richilde, Countess of Hainaut
Richilde, Countess of Mons and Hainaut( – 15 March 1086), was a ruling countess of Hainaut from c. 1050 until 1076, in co-regency with her husband Baldwin VI, Count of Flanders and son Baldwin II, Count of Hainaut.
She was also countess consort of Flanders by marriage to Baldwin VI, Count of Flanders.
She served as regent of Flanders during the minority of her son Arnulf III, Count of Flanders in 1070- 1071.
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.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.
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.
Margaret I, Countess of Flanders
Margaret I of Flanders (c. 1145 - died 15 November 1194) was ruling countess of Flanders "suo jure" from 1191 to her death.
She was the daughter of Thierry, Count of Flanders, and Sibylla of Anjou, and the heiress of her childless brother, Philip of Flanders.
Margaret I, Countess of Burgundy
Margaret I( 1310 – 9 May 1382), was a ruling Countess Palatine of Burgundy and Artois from 1361 and 1382.
She was also countess of Flanders, Nevers and Rethel by marriage to Louis I, Count of Flanders, and regent of Flanders during the minority of her son Louis II, Count of Flanders in 1346.
Baldwin V, Count of Flanders
Baldwin V of Flanders( c. 1012 – 1 September 1067) was Count of Flanders from 1035 until his death.
He was the son of Baldwin IV, Count of Flanders, who died in 1035.

Question: Who is Margaret I, Countess Of Flanders's paternal grandmother?
Answer: Gertrude of Flanders