Question: Who is the maternal grandfather of Margaret Of Holland, Countess Of Henneberg?

Margaret of Holland, Countess of Henneberg
Margaret of Henneberg (1234 – 26 March 1276) was a Dutch countess, known for a famous medieval legend.
She was a daughter of Count Floris IV of Holland and his wife, Matilda of Brabant.
Catherine of Henneberg
Catherine of Henneberg( c. 1334, in Schleusingen – 15 July 1397, in Meissen) was a Countess of Henneberg by birth and from 1347 by marriage Margravine of Meissen, Landgravine of Thuringia, etc.
She was the wife of Margrave Frederick the Severe of Meissen.
Via her, the House of Wettin inherited her father's Franconian possessions.
Matilda of Brabant, Countess of Holland
Mathilde (c. 1200 – 22 December 1267) was the fourth child and daughter of Mathilde of Flanders and Henry I, Duke of Brabant.
She married Henry II, Count Palatine of the Rhine (
died 1214) in Aachen in 1212 and later married Floris IV, Count of Holland on 6 December 1224.
William IV, Princely count of Henneberg-Schleusingen
Princely count William IV of Henneberg- Schleusingen(" c." 1475 – 24 January 1559), a member of the House of Henneberg, was a ruler of the Principality of Henneberg, within the Holy Roman Empire.
The son of William III of Henneberg, William inherited the Principality of Henneberg on 26 May 1480, when his father died, and reigned until his own death nearly eighty years later, on 24 January 1559.
William married Anastasia of Brandenburg, a daughter of Albert Achilles, Elector of Brandenburg.
In 1543 – 1544 William embraced the Protestant Reformation.
In 1554 he signed a treaty of inheritance with John Frederick II, Duke of Saxony.
William died in Salorno five years later.
However, when his successor George Ernest, the last Prince of Henneberg, died, both the Ernestine and the Albertine branches of the Wettin dynasty claimed his estates.
In 1660 they were finally divided between the Ernestine duchies of Saxe- Weimar and Saxe- Gotha and the Albertine Maurice of Saxe- Zeitz, while the lordship of Schmalkalden went to William IV, Landgrave of Hesse- Kassel, honouring an inheritance treaty of 1360.
Adelaide of Holland
Adelaide of Holland( – buried 9 April 1284), Countess of Hainaut, was a Dutch regent.
She was a daughter of Floris IV, Count of Holland and Matilda of Brabant.
She was also a sister of William II, Count of Holland and King of Germany.
She acted as regent for her nephew Count Floris V during his minority.
Elisabeth of Brunswick-Lüneburg
Elisabeth of Brunswick- Lüneburg( 1230 – 27 May 1266) was Queen of the Romans, Countess of Holland, and Countess of Zeeland as the wife of William II of Holland.
Gertrude of Saxony
Gertrude of Saxony (1030 – August 4, 1113), also known as Gertrude Billung, was a countess of Holland by marriage to Floris I, Count of Holland, and countess of Flanders by marriage to Robert I, Count of Flanders.
She was regent of Holland in 1061-1067 during the minority of her son Dirk V, and regent of Flanders during the absence of her spouse in 1086-1093.
Lutgardis of Luxemburg
Lutgardis of Luxembourg, also known as Liutgardis, Liutgarde and Lutgard,( 955 – ca. 1005 or possibly later) was a countess consort of Holland by marriage to Arnulf, Count of Holland.
She was the regent of Holland from 993 until 1005 during the minority of her son Dirk III of Holland.
Petronilla of Lorraine
Petronilla of Lorraine( 1082 – 23 May 1144) was Countess of Holland by marriage to Floris II, Count of Holland, and regent of the County of Holland during the minority of her son Dirk VI in 1121- 1129.
She was a daughter of Theodoric II, Duke of Lorraine and Hedwig of Formbach.
Eleanor Holland, Countess of Salisbury
Eleanor Holland, Countess of Salisbury( 1386- after 1413), was an English noblewoman, the daughter of Thomas Holland, 2nd Earl of Kent, a half- brother of King Richard II of England.
She was the first wife of Thomas Montagu, 4th Earl of Salisbury.
One of her brothers was Edmund Holland, 4th Earl of Kent, to whom she was co-heiress.
She is not to be confused with her eldest sister Alianore Holland, Countess of March who bore the same name.

Answer: Henry I