John Westley
Rev. John Westley( 1636 – 78) was an English nonconformist minister.
He was the grandfather of John Wesley( founder of Methodism).
Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.
He was the grandfather of singer/ poet Leonard Cohen.
Seisyll Bryffwrch
Seisyll Bryffwrch( fl. 1155-1175) was a Welsh- language poet.
Seisyll competed against and was defeated by Cynddelw in a contest for the role of chief court poet to Madog ap Maredudd, prince of Powys.
Seisyll's own compositions include elegies on the death of Owain Gwynedd and of Iorwerth Drwyndwn grandfather and father respectively of Llywelyn ab Iorwerth.
Seisyll also wrote poems in praise of the campaigns of the Lord Rhys.
Owain Gwynedd
Owain ap Gruffudd (23 or 28 November 1170) was King of Gwynedd, North Wales, from 1137 until his death in 1170, succeeding his father Gruffudd ap Cynan.
He was called "Owain the Great" (Welsh: "Owain Mawr") and the first to be styled "Prince of Wales".
He is considered to be the most successful of all the North Welsh princes prior to his grandson, Llywelyn the Great.
He became known as Owain Gwynedd ("Owain of Gwynedd") to distinguish him from the contemporary king of Powys Wenwynwyn, Owain ap Gruffydd
ap Maredudd, who became known as Owain Cyfeiliog.
Iorwerth Drwyndwn
Iorwerth ab Owain Gwynedd (or Iorwerth Drwyndwn meaning "the flat-nosed"), also called Edward (c. 1130–1174), was the eldest legitimate son of Owain Gwynedd (the king of Gwynedd) and his first wife Gwladys (Gladys)
ferch Llywarch.
He married Marared ferch Madog.
His son, Llywelyn the Great, eventually united the realm and became known as "Llywelyn Fawr" and is one of Wales's most famous monarchs.
Iorwerth received Nant Conwy as his inheritance from his father, Owain Gwynedd.
However, he did not receive the crown succession, as was the normal tradition, because of his nose defect (his sobriquet 'Trwyndwn' means broken-nosed).
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.
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
Zhao Shoushan
Zhao Shoushan( 12 November 1894 – 20 June 1965) was a KMT general and later Chinese Communist Party politician.
He is the grandfather of Zhao Leji.

Question: Who is the paternal grandfather of Iorwerth Drwyndwn?
Answer: Gruffudd ap Cynan