Tudwal Gloff
Tudwal Gloff (or ; born c. 860) was the youngest of the four sons of Rhodri the Great.
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.
John Mackay (poet)
John Mackay( 1656–1754), known as( The Blind Piper), was a Scottish Gaelic poet and composer, and the grandfather of William Ross.
Abd al-Muttalib
Abd al- Muttalib Shaybah ibn Hashim( c. 497 – 578) was the grandfather of Islamic prophet Muhammad.
Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.
He was the grandfather of singer/ poet Leonard Cohen.
John Westley
Rev. John Westley( 1636 – 78) was an English nonconformist minister.
He was the grandfather of John Wesley( founder of Methodism).
Rhodri the Great
Rhodri ap Merfyn (820–878), later known as Rhodri the Great , succeeded his father, Merfyn Frych, as King of Gwynedd in 844.
Rhodri annexed Powys c. 856 and Seisyllwg c. 871.
He is called "King of the Britons" by the "Annals of Ulster.
" In some later histories, he is referred to as "King of Wales", although the title is anachronistic and his realm did not include southern Wales.
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.
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 Tudwal Gloff's paternal grandfather?
Answer: Merfyn Frych