Joanna of Châtillon
Joanna of Châtillon or" Joan",;( c. 1285 – 16 January 1354) was the wife of Walter V of Brienne( 1305).
She was Duchess of Athens by marriage( 1308 – 1311).
She was the daughter of Gaucher V de Châtillon, Constable of France and Isabelle de Dreux.
Her paternal grandparents were Gaucher IV de Châtillon and Isabelle de Villehardouin.
Her maternal grandparents were Robert de Dreux, Viscount of Chateaudun and Isabelle de Villebéon.
Isabelle de Meulan
Isabelle de Meulan, Dame de Mayenne, Dame de Craon (
c. 1148 – 10 May 1220) was a French noblewoman, being the daughter of Waleran de Beaumont, 1st Earl of Worcester, Count of Meulan.
Isabelle married twice; firstly to Geoffroy, Seigneur de Mayenne, and secondly to Maurice II, Sire de Craon.
Her eldest son Juhel III de Mayenne was a celebrated Crusader.
Abd al-Muttalib
Abd al- Muttalib Shaybah ibn Hashim( c. 497 – 578) was the grandfather of Islamic prophet Muhammad.
Geoffrey Scott (architectural historian)
Geoffrey Scott (11 June 1884 – 14 August 1929) was an English scholar and poet, known as a historian of architecture.
His biography of Isabelle de Charrière entitled "The Portrait of Zelide" won the 1925 James Tait Black Memorial Prize.
Isabelle de Hertogh
Isabelle de Hertogh is a Belgian actress.
Fred Le Deux
Frederick" Fred" Le Deux( born 4 December 1934) was an Australian rules footballer who played with Geelong in the Victorian Football League( VFL).
He is the grandfather of Tom Hawkins.
Henry Krause
Henry J." Red" Krause, Jr.( August 28, 1913 – February 20, 1987) was an American football offensive lineman in the National Football League for the Brooklyn Dodgers and the Washington Redskins.
He played college football at St. Louis University.
He is the grandfather of Jennifer Krause
He is the great grandfather of Payton Hoeing
Waleran de Beaumont, 1st Earl of Worcester
Waleran de Beaumont, Count of Meulan, 1st Earl of Worcester (1104 – 9 April 1166, Preaux), was the son of Robert de Beaumont, 1st Earl of Leicester and Elizabeth de Vermandois, and the twin brother of Robert de Beaumont, 2nd Earl of Leicester.
He is not referred to by any surname in a contemporary document other than 'Waleran son of Count Robert'.
Kaya Alp
Kaya Alp was, according to Ottoman tradition, the son of Kızıl Buğa and the father of Suleyman Shah, who was, in turn, the grandfather of Ertuğrul, and the great grandfather of the Ottoman Empire founder, Osman I.
Pauline de Meulan
Pauline de Meulan( 2 November 1773 in Paris — 1 August 1827) was a French writer and journalist.

Question: Who is Isabelle De Meulan's paternal grandfather?
Answer: Robert de Beaumont, 1st Earl of Leicester