Helen Butler
Helen Butler (died 28 January 1631), also known as the Honorable Helen Butler, was the daughter of Edmund Butler, 2nd Viscount Mountgarret and Grizel FitzPatrick.
She married her second cousin Walter Butler, 11th Earl of Ormond.
Their common great-grandfather was Piers Butler, 8th Earl of Ormond.
She had three sons and nine daughters:
Thomas Butler of Garryricken
Thomas Butler of Garryricken (died 1738), also known as Thomas Butler of Kilcash and sometimes distinguished by his title of Colonel, was an Irish landowner.
He succeeded to the estates of his grandfather Richard Butler of Kilcash.
His brother Christopher was the Catholic Archbishop of Cashel and Emly.
Thomas Butler fought for the Jacobites in the Williamite war and was taken prisoner at the Battle of Aughrim.
His son John became, "de jure", the 15th Earl of Ormond.
Edmund Butler, 2nd Baron Cahir
Edmond Butler, 2nd Baron Cahir( died 1560) was the son of Thomas Butler, 1st Baron Cahir and the grandson of Thomas Butler of Cahir.
The title became extinct upon his death but was revived in favour of his first cousin, Theobald Butler, 1st Baron Cahir( of the second creation).
Thomas Butler, Viscount Thurles
Thomas Butler, Viscount Thurles (before 1596 – 15 December 1619) was the son and heir apparent of Walter Butler, 11th Earl of Ormond (1559 – 1632/3) (whom he predeceased) and Helen Butler.
He resided at Thurles Castle, Thurles, County Tipperary.
He was the father of the noted Anglo-Irish statesman and Royalist commander James Butler, 1st Duke of Ormonde.
Richard Butler of Kilcash
Richard Butler of Kilcash( 1615–1701) was the third son of Thomas Butler, Viscount Thurles and brother of James, 1st Duke of Ormonde.
Richard's descendants would take over the earldom of Ormond following the failure in 1658 of the senior branch of the family.
Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.
He was the grandfather of singer/ poet Leonard Cohen.
Anne Hankford
Anne Hankford( c. 1431 – 13 November 1485) was the first wife of Thomas Butler, 7th Earl of Ormond( c. 1426- 3 August 1515).
She was the great- grandmother of Anne Boleyn
Jason Butler Harner
Jason Thomas Butler Harner( born October 9, 1970) is an American actor.
Abd al-Muttalib
Abd al- Muttalib Shaybah ibn Hashim( c. 497 – 578) was the grandfather of Islamic prophet Muhammad.
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.

Question: Who is the maternal grandfather of Thomas Butler, Viscount Thurles?
Answer: Edmund Butler, 2nd Viscount Mountgarret