John Westley
Rev. John Westley( 1636 – 78) was an English nonconformist minister.
He was the grandfather of John Wesley( founder of Methodism).
Hélène Langevin-Joliot
Hélène Langevin-Joliot (born 19 September 1927) is a French nuclear physicist.
She was educated at the "IN2P3"  at Orsay, a laboratory which was set up by her parents Irène Joliot-Curie and Frédéric Joliot-Curie.
She is a member of the French government's advisory committee.
Currently, she is a professor of nuclear physics at the Institute of Nuclear Physics at the University of Paris and a Director of Research at the CNRS.
She is also known for her work in actively encouraging women to pursue careers in scientific fields.
She is Chairperson of the panel that awards the Marie Curie Excellence award, a prize given to outstanding European researchers.
She was President of the French Rationalist Union from 2004 to 2012.
Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.
He was the grandfather of singer/ poet Leonard Cohen.
Noëlle Roger
Noëlle Roger, the pen name of Hélène Pittard (September 25, 1874 – October 5, 1953), was a Swiss author writing in French.
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.
Prithvipati Shah
Prithvipati Shah( ?–1716) was the king of the Gorkha Kingdom in the Indian subcontinent, present- day Nepal.
He was the grandfather of Nara Bhupal Shah.
Irène Joliot-Curie
Irène Joliot-Curie (12 September 1897 – 17 March 1956) was a French scientist with Polish ancestry, the daughter of Marie Sklodowska Curie and Pierre Curie and the wife of Frédéric Joliot-Curie.
Jointly with her husband, Joliot-Curie was awarded the Nobel Prize in Chemistry in 1935 for their discovery of artificial radioactivity.
This made the Curies the family with the most Nobel laureates to date.
Both children of the Joliot-Curies, Hélène and Pierre, are also esteemed scientists.
Guillaume Wittouck
Guillaume Wittouck( 1749- 1829) was a Belgian lawyer and High Magistrate.
He was the Grandfather of industrialist Paul Wittouck.
Fujiwara no Nagara
, also known as Fujiwara no Nagayoshi, was a Japanese statesman, courtier and politician of the early Heian period.
He was the grandfather of Emperor Yōzei.

Question: Who is the maternal grandfather of Hélène Langevin-Joliot?
Answer: Pierre Curie