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.
Teresa Lourenço
Teresa Gille Lourenço( Lisbon, 1330 –?), was the lover of King Peter I of Portugal and mother of King John I of Portugal.
Sancho I of Portugal
Sancho I , nicknamed "the Populator" , King of Portugal (Coimbra, 11 November 115426 March 1211)
was the second but only surviving legitimate son and fifth child of Afonso I of Portugal by his wife, Maud of Savoy.
Sancho succeeded his father and was crowned in Coimbra when he was 31 years old on 9 December 1185.
He used the title King of Silves from 1189 until he lost the territory to Almohad control in 1191.
Diogo, Constable of Portugal
Diogo of Portugal( 1425–1443) was a Portuguese royal prince, who briefly served as Constable of Portugal and Master of the Order of Santiago.
Diogo was the eldest son of John, Lord of Reguengos de Monsaraz, Infante of Portugal, and of his wife( and niece) Isabella of Barcelos.
Through his father, Diogo was the grandson of King John I of Portugal and through his mother, the grandson of Afonso of Barcelos( future first duke of Braganza).
John of Reguengos had been the master of the Order of Santiago since 1418 and Constable of Portugal since 1431.
Upon John's premature death in October 1442, the Portuguese regent, Peter of Coimbra decided to appoint John's son Diogo as the new Constable of Portugal.
Diogo was elected on 24 January 1443, as 11th Master of the Order of Santiago.
Diogo died a few days later, without issue.
Peter appointed his own son, also named Peter, to succeed him as constable.
These appointments were contested by Diogo's half- uncle( and grandfather), Afonso, Count of Barcelos.
Afonso had married the daughter of the late beatified constable Nuno Álvares Pereira, and believed their son, Afonso of Ourem, had superior rights to succeed as Constable of Portugal.
Peter of Coimbra challenged Barcelos and Ourem to provide documentary proof of the legitimacy of this lineage( which they were unable to produce).
Peter of Coimbra attempted to mollify them by creating the title of Duke of Braganza, and investing it in Afonso of Barcelos.
However, this failed to heal the breach between Peter and Afonso, which would only grow with time.
Afonso, Prince of Portugal (1526)
Afonso, Prince of Portugal was the first son of king John III of Portugal and his queen, Catherine of Austria.
He was the Prince of Portugal but died in the same year he was born, in 1526.
Duke Peter of Oldenburg
Duke Constantine Frederick Peter of Oldenburg( 26 August 1812 in Yaroslavl, Russian Empire – 14 May 1881 in St. Petersburg, Russian Empire) was a Duke of the House of Oldenburg.
He was the grandfather of Duke Peter of Oldenburg as well as grandfather of Grand Duke Nicholas Nikolaevich, General of the Imperial Russian Army during World War I.
His great- great grandson, Nicholas Romanov, was the President of the Romanov Family Association until his death in 2014.
Peter of Oldenburg was a scholar and philanthropist.
He was also noted composer of music.
In 1857 he composed the music for Marius Petipa's ballet" La Rose, la Violette et le Papillon".
The" Pas d' Esclave" from the ballet" Le Corsaire", which is taken from his score for this work, is still heard in theatres all over the world.
Peter of Bergamo
Peter of Bergamo also called Peter of Almadura( 1400 ca.- 1482) was an Italian Dominican theologian.
Peter I, Count of Urgell
Peter I  (February 23, 1187 - June 2, 1258) was the second son of King Sancho I of Portugal and his wife Dulce, infanta of Aragon, and would eventually become
Count of Urgell and Lord of the Balearic Islands.
Beatrice, Countess of Alburquerque
Beatrice of Portugal was Countess of Alburquerque as the wife of Sancho Alfonso of Alburquerque.
She was the daughter of Peter I of Portugal and his wife Inês de Castro.

Question: Who is Peter I, Count Of Urgell's paternal grandfather?
Answer: Afonso I of Portugal