Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.
He was the grandfather of singer/ poet Leonard Cohen.
Ailill Caisfiaclach
Ailill Caisfiaclach ("having crooked/hateful teeth"), son of Connla Cáem, was, according to medieval Irish legends and historical traditions, a High King of Ireland.
He succeeded his father, and reigned for twenty-five years, until he was killed by Adamair, the son of Fer Corb
the man who had killed Ailill's grandfather.
The "Lebor Gabála Érenn" synchronises his reign with that of Ptolemy V Epiphanes in Egypt (204–181 BC).
Geoffrey Keating's "Foras Feasa ar Éirinn" dates his reign from 315 to 290 BC, the "Annals of the Four Masters" from 443 to 418 BC.
Connla Cáem
Connla Cáem ("the beautiful"), also known as Connla Cruaidchelgach ("bloody blade"), son of Irereo, was, according to medieval Irish legend and historical tradition, a High King of Ireland.
Abd al-Muttalib
Abd al- Muttalib Shaybah ibn Hashim( c. 497 – 578) was the grandfather of Islamic prophet Muhammad.
Guillaume Wittouck
Guillaume Wittouck( 1749- 1829) was a Belgian lawyer and High Magistrate.
He was the Grandfather of industrialist Paul Wittouck.
Henry Bryant (naturalist)
Henry Bryant( May 12, 1820 – February 2, 1867) was an American physician and naturalist.
He was the grandfather of Henry Bryant Bigelow.
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.
Prithvipati Shah
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He was the grandfather of Nara Bhupal Shah.
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.
John Westley
Rev. John Westley( 1636 – 78) was an English nonconformist minister.
He was the grandfather of John Wesley( founder of Methodism).

Question: Who is Ailill Caisfiaclach's paternal grandfather?
Answer: Irereo