Costantino Mario Ruspoli, 4th Prince of Poggio Suasa
Constantino Mario dei Principi Ruspoli( born 29 June 1971), son of Marcantonio Mario Dimitri Ruspoli, 3rd Prince of Poggio Suasa, and his second wife Gleide Portela Chagas( 1935 – 2002), is the 4th Principe di Poggio Suasa and Prince of the Holy Roman Empire.
George Louis, Prince of Erbach-Schönberg
George Louis, Prince of Erbach- Schönberg( 1 January 190327 January 1971) was the 3rd Prince of Erbach- Schönberg, elder son of Alexander, 2nd Prince of Erbach- Schönberg.
Marcantonio Mario Dimitri Ruspoli, 3rd Prince of Poggio Suasa
Marcantonio Mario Dimitri dei Principi Ruspoli (November 28, 1926 – August 1, 2003)
was the 3rd Principe di Poggio Suasa and Prince of the Holy Roman Empire, son of Costantino Ruspoli
(Costantino is an eldest son of Mario Ruspoli, 2nd Prince of Poggio Suasa), and wife Elisabeth Catherine Adrienne Marie Anne Comtesse van der Noot d'Assche.
Bartolomeo Ruspoli and Khevenhüller-Metsch
Bartolomeo Ruspoli and Khevenhüller- Metsch, dei principi Ruspoli( October 26, 1800 – 1872) was an Italian aristocrat, Prince of the Holy Roman Empire, son of Francesco Ruspoli, 3rd Prince of Cerveteri and second wife Leopoldina Countess von Khevenhüller- Metsch.
He had four brothers, among others, Alessandro Ruspoli, 4th Prince of Cerveteri, and Camillo Ruspoli, Duke of Sueca.
He was colonel of the Piedmontese army, in which he participates in the wars of the Italian resurgence.
Paralyzed from below waist by the blast of a grenade, he continued to participate in wheelchair battles pushed by his assistant.
Bartolomeo is the ancestor of the Line III of the Princes Ruspoli.
His son Emanuele Ruspoli was named first prince of Poggio- Suasa after participating in the Italian unification and being the first Mayor of the Italian Rome.
He was the grandfather of Donna Emanuella de Dampierre Ruspoli, Duchess of Segovia and Duchess of Anjou by her marriage to Infante Don Jaime, son of Alfonso XIII of Spain.
Emanuele is the founder of the third Ruspoli line: The Princes of Poggio- Suasa.
Camillo Ruspoli, 2nd Prince of Candriano
Camillo dei Principi Ruspoli( 10 January 1882 – 5 September 1949), was the 2nd and last Principe di Candriano and Prince of the Holy Roman Empire, son of Emanuele Ruspoli, 1st Prince of Poggio Suasa, and second wife Laura Caracciolo dei Principi di Torella, Duchi di Lavello, Marchesi di Bella.
His maternal uncle, Giuseppe Caracciolo( 1849 – 1920), Patrizio Napolitano, married twice and without issue, was the 1st Prince of Candriano( formerly Marquis of Candriano)( 12 May 1893 – 1 October 1920).
Francesco Ruspoli, 3rd Prince of Cerveteri
Francesco, Prince Ruspoli, 3rd Prince of Cerveteri, 3rd Marquis of Riano, 8th Count of Vignanello( February 19, 1752 – March 8, 1829) was the 3rd Prince of Cerveteri, 3rd Marquis of Riano and 8th Count of Vignanello, son of Alessandro Ruspoli, 2nd Prince of Cerveteri and second wife and first cousin Prudenza dei Conti Marescotti- Capizucchi.
His uncle was Bartolomeo Ruspoli.
In 1792 he was created Prince of the Holy Roman Empire both he and his male descendants, by the Emperor Francis II.
Emanuele Ruspoli, 1st Prince of Poggio Suasa
Emanuele Francesco Maria dei Principi Ruspoli, 1 Prince of Poggio Suasa (December 30, 1837 – November 29, 1899)
was an Italian and a Holy Roman Empire prince who twice served as the Mayor of Rome.
Alessandro Ruspoli, 4th Prince of Cerveteri
Alessandro, Principe Ruspoli( October 5, 1784 – October 31, 1842) was the 4th Prince of Cerveteri, 4th Marquis of Riano, 9th Count of Vignanello and Prince of the Holy Roman Empire, son of Francesco Ruspoli, 3rd Prince of Cerveteri and second wife HIH Leopoldina Gräfin von Khevenhüller- Metsch.
He had for brothers, among others, Camillo Ruspoli, Duke of Sueca, and Bartolomeo Ruspoli and Khevenhüller- Metsch.
His granduncle was Bartolomeo Ruspoli.
Alessandro is the ancestor of the Line I of the Princes Ruspoli.
Mario Ruspoli, 2nd Prince of Poggio Suasa
Mario dei Principi Ruspoli (October 16, 1867 –
January 16, 1963) was an Italian prince, son of Emanuele Ruspoli, 1st Prince of Poggio Suasa and first wife Princess Caterina Vogoride-Conachi.
He was the 2nd Prince of Poggio Suasa and Prince of the Holy Roman Empire.
He was responsible for the brief development of Chatsworth, New Jersey as a resort in the early 20th Century.
Francesco Alvaro Maria Giorgio Ruspoli, 1st Duke of Morignano
" Don" Francesco Alvaro Maria Giorgio dei Principi Ruspoli( April 19, 1891 – March 2, 1970) was an Italian nobleman, the 1st Duca di Morignano, Nobile di Viterbo e di Orvieto, Patrizio Romano and Prince of the Holy Roman Empire.
Born in Rome, he was the son of Emanuele Ruspoli, 1st Prince of Poggio Suasa and third wife Josephine Mary Beers- Curtis.

Question: Who is Marcantonio Mario Dimitri Ruspoli, 3Rd Prince Of Poggio Suasa's paternal grandfather?
Answer: Emanuele Ruspoli, 1st Prince of Poggio Suasa