Marie of Brittany, Countess of Saint-Pol
Marie of Brittany( 1268–1339) was the daughter of John II, Duke of Brittany, and Beatrice of England.
She is also known as Marie de Dreux.
Françoise de Dinan
Françoise de Dinan( 1436- 1499), was a French heiress, courtier and educator.
She was the governess of Anne of Brittany.
She was the daughter and heir of Jacques de Dinan( d. 1444), lord of Beaumanoir and chamberlain at the court of Brittany, and Catherine de Rohan.
Sh was also the heir of her paternal uncle Bertrand de Dinan( d. 1444), Marshall of Bretagne, Lord of Montafilant, Chateaubriant and Huguetières.
She was abducted by and forced to marry Gilles of Brittany, brother of Francis I, Duke of Brittany and Peter II, Duke of Brittany, in 1444.
She was widowed in 1450, when her spouse was imprisoned and died on the instigation of Arthur de Montauban, who wished to marry her.
By the help of Françoise d'Amboise, she married Guy XIV de Laval in 1451.
In 1488, she was appointed governess to Anne of Brittany and her sister Isabelle.
She played an active role on the political marriage arrangements surrounding Anne.
In 1494, she remarried the noble Jean de Proisy.
Margaret of Foix
Margaret of Foix( French:" Marguerite de Foix"; c. 1449 – 15 May 1487) was Duchess of Brittany from 1474 to 1486 by marriage to Francis II, Duke of Brittany.
Gourmaëlon
Gourmaëlon or Wrmaelon( died 913/ 4), was the Count of Cornouaille and" de facto" ruler of Brittany from 907 – c. 914.
As ruler of Brittany he was considered" Prince de Bretagne" in some chronicles and histories.
His actual history is among the least well documented of the early medieval rulers of Brittany.
His reputed time of rule coincides with a dramatic increase in Viking invasions that ultimately led up to the Viking Occupation of Brittany that began after his death.
He is believed to have been named Count of Cornouaille by Alan I, King of Brittany near the end of his reign in 907.
After Alan I's death in 907 he disputed the right of Alan's heirs to rule Brittany and fought for the control of the kingdom, albeit without claiming the title king.
His life and activities are sparsely recorded in historical documents save for several donations to the Breton churches of the day.
In a donation to the monastery of Plélan in 910 he is identified as ruler of Brittany.
At Redon in 913 he is identified as" Count Gourmaelon, the Breton monarch."
He is understood to have died in 913( or 914) in a battle with invading Vikings.
No subsequent ruler of Brittany is recorded in histories or chronicles of the period until the return of Alan II, Duke of Brittany, known as Alan Barbetorte, from England c. 937–938.
Blanche of Brittany
Blanche of Brittany( 1271 – 1327) was a daughter of John II, Duke of Brittany, and his wife Beatrice of England.
She is also known as Blanche de Dreux.
Through her mother she was the granddaughter of King Henry III of England and Eleanor of Provence.
Conan II, Duke of Brittany
Conan II of Rennes (c. 1033 – 11 December 1066) was Duke of Brittany, from 1040 to his death.
Conan was the eldest child and heir of Alan III, Duke of Brittany by his wife Bertha of Blois, and member of the House of Rennes.
He was the elder brother of Hawise, who succeeded him as "suo jure" duchess.
Bertha of Blois
Bertha of Blois (French: "Berthe de Blois"; c. 1005 — c. 1080), was a Duchess consort of Brittany and a countess consort of Maine, married in 1018 to Alain III, Duke of Brittany, and in 1046 to Hugh IV, Count of Maine.
She was the daughter of Odo II, Count of Blois and Ermengarde of Auvergne.
Guerech, Duke of Brittany
Guerech of Brittany, was Count of Nantes and Duke of Brittany from 981 to 988.
Maria of Brabant, Duchess of Bavaria
Maria of Brabant( 1226–1256) was a daughter of Henry II, Duke of Brabant, and Maria of Swabia.
She married Louis II, Duke of Bavaria, being the first of three wives.
Margaret of Huntingdon, Duchess of Brittany
Margaret of Huntingdon( 1145–1201) was a Scottish princess and Duchess of Brittany.
She was the sister of Scottish kings Malcolm IV and William I, wife of Conan IV, Duke of Brittany, and the mother of Constance, Duchess of Brittany.
Her second husband was Humphrey de Bohun, hereditary Constable of England.
Following her second marriage, Margaret styled herself as the Countess of Hereford.

Question: Who is the maternal grandfather of Conan Ii, Duke Of Brittany?
Answer: Odo II, Count of Blois