Margaret of Valois, Countess of Blois
Margaret of Valois (1295–1342) was a French noblewoman.
She was a daughter of Charles, Count of Valois, and his first wife, Margaret, Countess of Anjou.
She was also a sister of King Philip VI of France.
In 1310, she married Guy I, Count of Blois.
They had three children together:
Louis II, Count of Blois
Louis II of Châtillon( d. 26 August 1346, battle of Crécy), son of Guy I, Count of Blois and Margaret of Valois, was count of Blois and lord of Avesnes 1342 – 1346.
In 1340 in Soissons, he married Jeanne of Avesnes, Countess of Soissons( d. 1350), daughter of John of Avesnes, Lord of Beaumont.
They had three children:
Louis was killed at the Battle of Crécy.
Marie of Valois, Duchess of Calabria
Marie of Valois( 1309 – 23 October 1331), was the eldest daughter of Charles of Valois by his third wife Mahaut of Châtillon.
She was a member of the House of Valois.
One of her five children was Queen Joanna I of Naples.
Charles, Count of Valois
Charles of Valois (12 March 1270 – 16 December 1325), the third son of Philip III of France and Isabella of Aragon, was a member of the House of Capet and founder of the House of Valois, whose rule over France would start in 1328.
Charles ruled several principalities.
He held in appanage the counties of Valois, Alençon and Perche.
Through his marriage to Margaret of Anjou, he became Count of Anjou and Maine.
Through his marriage to Catherine I, titular empress of the Latin Empire, he was titular Latin Emperor of Constantinople from 1301–1307, although he ruled from exile and only had authority over Crusader States in Greece.
The grandson of Louis IX of France, Charles of Valois was a son, brother, brother-in-law and son-in-law of kings or queens (of France, Navarre, England and Naples).
His descendants, the House of Valois, would become the royal house of France three years after his death, beginning with his son Philip VI of France.
Guy I, Count of Blois
Guy I of Châtillon, Count of Blois( died 12 August 1342), son of Hugh II of Châtillon and Beatrix of Dampierre, was Count of Blois and Lord of Avesnes 1307 – 1342.
In 1310, he married Margaret of Valois, daughter of Charles of Valois and sister of Philip VI of France.
They had three children:
He took part in the expedition of Louis X of France against his uncle Robert III of Flanders in 1315, and in the early stages of the Hundred Years' War.
Theobald III, Count of Blois
Theobald III of Blois( French:" Thibaut")( 1012–1089) was count of Blois, Meaux and Troyes.
He was son of Odo II, Count of Blois and Ermengarde of Auvergne.
Alix of France
Alix of France( July – August 1150 – 1197/1198) was countess consort of Blois by marriage to Theobald V, Count of Blois.
She was regent of Blois during the absence of her spouse in 1190- 1191, and regent during the minority of Louis I, Count of Blois from 1191 until 1197.
Margaret, Countess of Blois
Margaret of Blois( French:" Marguerite"; died 1230) was" suo jure" Countess of Blois from 1218 to 1230, in what is now France.
Mary, Countess of Blois
Mary, Countess of Blois, also known as" Marie of Avesnes",( 1200 – 1241) was countess of Blois from 1230 to 1241.
She was the daughter of Walter of Avesnes and Margaret of Blois.
In 1226, Mary married Hugh I of Châtillon, a count from Châtillon- sur- Marne, son of Gaucher III of Châtillon and Elisabeth of Saint Pol.
They had five children:
Her eldest son John, succeeded her in Blois.
Margaret, Countess of Anjou
Margaret, Countess of Anjou( 1272 – 31 December 1299) was Countess of Anjou and Maine in her own right and Countess of Valois, Alençon, Chartres and Perche by marriage.
Margaret's father was King Charles II of Naples, whilst her husband was Charles of Valois, and her older brother was Saint Louis of Toulouse; her nephew was Charles I of Hungary.

Question: Who is Margaret Of Valois, Countess Of Blois's paternal grandfather?
Answer: Philip III of France