Isabella of Burgundy, Queen of Germany
Isabella of Burgundy (1270 – August 1323), Lady of Vieux-Château, was the second and last Queen consort of Rudolph I of Germany.
She was the second daughter of Hugh IV, Duke of Burgundy and his second wife Beatrice of Navarre.
Isabella was betrothed in 1272 to Charles of Flandres.
He was born in 1266 to the later Robert III of Flanders and his first wife Blanche of Sicily.
Her betrothed died in 1277.
On 6 February 1284, Isabella became the second wife of Rudolf I of Germany.
The bride was fourteen years old and the groom almost sixty-six.
Their marriage remained childless.
Rudolph died on 15 July 1291.
He was succeeded as Duke of Austria by his co-ruling sons
Albert I and Rudolph II.
She returned to the Court of Burgundy and was granted the title of "Lady of Vieux-Château" on 20 November 1294.
She had a second marriage to Pierre IX de Chambly, Lord of Neaufles who died c. 1319.
Sibylla of Burgundy, Duchess of Burgundy
Sybilla of Burgundy( 1065 – 1103), was a French noble, Duchess consort of Burgundy by marriage to Eudes I, Duke of Burgundy.
She was a daughter of William I, Count of Burgundy and Stephanie.
She was married to Eudes I, Duke of Burgundy in 1080.
Children:
Joan III, Countess of Burgundy
Joan III of Burgundy( 1/2 May 1308 – 10/15 August 1347), also known as Joan of France was a reigning Countess of Burgundy and Artois in 1330 – 1349, She was also Duchess of Burgundy by marriage to Odo IV, Duke of Burgundy.
She was the eldest daughter of King Philip V of France and Countess Joan II of Burgundy.
Agnes of France, Duchess of Burgundy
Agnes of France( c. 1260 – 19 December 1327) was a Duchess of Burgundy by marriage to Robert II, Duke of Burgundy.
She served as regent of Burgundy during the minority of her son in 1306 – 1311.
Mary of Burgundy
Mary( 13 February 1457 – 27 March 1482), Duchess of Burgundy, reigned over many of the territories of the Duchy of Burgundy, now mainly in France and the Low Countries, from 1477 until her death.
As the only child of Charles the Bold, Duke of Burgundy, and his wife Isabella of Bourbon, she inherited the duchy upon the death of her father in the Battle of Nancy on 5 January 1477.
Owing to the great prosperity of many of her territories, Mary was often referred to as Mary the Rich.
Isabella of France, Dauphine of Viennois
" For other persons named Isabella of France, see Isabella of France( disambiguation)" Isabella of France and Burgundy( 1310 – April 1348) was the daughter of Philip V of France and Joan II, Countess of Burgundy.
Beatrice of Navarre, Duchess of Burgundy
Beatrice of Navarre (1242? – 1295), was Duchess of Burgundy, by marriage to Hugh IV, Duke of Burgundy.
She was a daughter of Theobald I of Navarre and his third wife Margaret of Bourbon.
Her siblings included Theobald II of Navarre and Henry I of Navarre.
She is also known as Beatrix of Champagne.
Tahira Wasti
Tahira Wasti( 1944 – March 11, 2012) was a well- known Pakistani writer and television actress.
She is best known for portrayal of Isabella of Castile in the TV drama" Shaheen".
Florine of Burgundy
Florine of Burgundy( 1083–1097) was a French crusader.
She was the daughter of Eudes I, Duke of Burgundy and Sybilla of Burgundy.
Her maternal grandfather was William I, Count of Burgundy.
Florine was married to Sweyn the Crusader, a son of Sweyn II of Denmark.
Isabella of Bourbon
Isabella of Bourbon, Countess of Charolais( 1434 – 25 September 1465) was the second wife of Charles the Bold, Count of Charolais and future Duke of Burgundy.
She was a daughter of Charles I, Duke of Bourbon and Agnes of Burgundy, and the mother of Mary of Burgundy, heiress of Burgundy.

Question: Who is the maternal grandfather of Isabella Of Burgundy, Queen Of Germany?
Answer: Theobald I of Navarre