Sizzo, Prince of Schwarzburg
Günther Sizzo, Prince of Schwarzburg( 3 June 1860 – 24 March 1926) was the head of the House of Schwarzburg and pretender to the principalities of Schwarzburg- Rudolstadt and Schwarzburg- Sondershausen.
Friedrich Günther, Prince of Schwarzburg
Friedrich Günther, Prince of Schwarzburg (5 March 1901 – 9 November 1971) was the final head of the House of Schwarzburg and heir to the formerly sovereign principalities of Schwarzburg-Rudolstadt and Schwarzburg-Sondershausen.
Karl Harst
Karl Harst( fl. 1540) was a sixteenth- century diplomat from the German Duchy of Cleves.
He was the Duke of Cleves' representative in London during the marriage of Henry VIII of England and his fourth wife, Anne of Cleves.
Charles Gonthier, Prince of Schwarzburg-Sondershausen
Charles Gonthier, Prince of Schwarzburg-Sondershausen (7 August 1830 – 28 March 1909) was the ruler of the principality of Schwarzburg-Sondershausen, a constituent state of the German Empire, and head of the House of Schwarzburg from 17 July 1880 until his death.
Albrecht VII, Count of Schwarzburg-Rudolstadt
Albrecht VII, Count of Schwarzburg-Rudolstadt (16 January 1537 – 10 April 1605) was Count of Schwarzburg and founder of the Line of Schwarzburg-Rudolstadt, which later received the title of Prince.
He was the youngest of the surviving sons of Günther XL, Count of Schwarzburg-Blankenburg and his wife Countess Elisabeth zu Ysenburg-Büdingen in Birstein.
Günther VII, Count of Schwarzburg-Blankenburg
Count Günther VII of Schwarzburg( † 1274) was Count of Schwarzburg- Blankenburg from 1236 until his death.
Henry VII, Count of Schwarzburg-Blankenburg
Henry VII, Count of Schwarzburg- Blankenburg, also known as" Henry VI"( before 1285 – 11 November 1324) was the ruling Count of Schwarzburg- Blankenburg from 1285 until his death.
Elisabeth of Cleves, Countess of Schwarzburg-Blankenburg
Elisabeth of Cleves was the daughter of Adolph I, Duke of Cleves and Marie of Burgundy, Duchess of Cleves.
She married Count Henry XXVI of Schwarzburg-Blankenburg, on July 15, 1434.
Mary of Burgundy, Duchess of Cleves
Mary of Burgundy, Duchess of Cleves (1393 – 30 October 1466) was the second child of John the Fearless and Margaret of Bavaria, and an elder sister of Philip the Good.
Born in Dijon, she became the second wife of Adolph, Count of Mark in May 1406.
He was made the 1st Duke of Cleves in 1417.
They were the grandparents of King Louis XII of France and the great-grandparents of John III, Duke of Cleves, father of Anne of Cleves, who was fourth Queen consort of Henry VIII of England.
By their daughter, Catherine, they were ancestors of Mary, Queen of Scots.
The Duke and Duchess of Cleves lived at Wijnendale Castle in West Flanders.
She died in Cleves in present-day Monterberg, Kalkar.
Ludmilla Elisabeth of Schwarzburg-Rudolstadt
Ludmilla Elisabeth of Schwarzburg- Rudolstadt( also" Ludomilla" or" Ludämilie"; 7 April 1640 – 12 March 1672 in Rudolstadt) was a German noblewoman and a hymn poet.
She was a Countess of Schwarzburg- Rudolstadt by birth.

Question: Who is Elisabeth Of Cleves, Countess Of Schwarzburg-Blankenburg's maternal grandfather?
Answer: John the Fearless