James FitzGerald, 6th Earl of Desmond
James FitzGerald, 6th Earl of Desmond (d. 1462), called 'the Usurper', was the youngest son of Gerald FitzGerald, 3rd Earl of Desmond, and Lady Eleanor, daughter of James Butler, 2nd Earl of Ormond.
Thomas FitzGerald, 5th Earl of Desmond
Thomas FitzGerald, 5th Earl of Desmond( c. 1386 – 1420), was the only son of John FitzGerald, 4th Earl of Desmond.
Upon John's death in 1399, Thomas succeeded to the earldom of Desmond, which lay in Munster, in the southwest of Ireland.
In 1418, Thomas was dispossessed of his lands and deprived of his earldom by his paternal uncle, James FitzGerald, 6th Earl of Desmond, after Thomas had concluded a marriage far below his station to Catherine MacCormac of Abbeyfeale; Catherine was the daughter one of Thomas's dependants, William MacCormac, known as" the Monk of Feale."
A marriage between a man of Norman blood and a woman of Gaelic ancestry was in violation of the Statutes of Kilkenny.
This ill- fated romance was the subject of the air" Desmond's Song" by the Irish poet Thomas Moore.
After the loss of his earldom, Thomas withdrew to France, where he" died at Rouen, 10th August 1420, and was buried at Paris' with great and mighty show, where the two kings of England and France were present.'"
James FitzGerald, 8th Earl of Desmond
James FitzGerald, 8th Earl of Desmond( 1459 – 1487) was the son of Thomas FitzGerald, 7th Earl of Desmond and his wife, Ellice de Barry, daughter of William Barry, 8th Baron Barry, and Ellen de la Roche.
Thomas FitzGerald, 7th Earl of Kildare
Thomas FitzJohn FitzGerald, 7th Earl of Kildare( – 25 March 1477), was an Irish peer and statesman of the fifteenth century who held the office of Lord Chancellor of Ireland.
John FitzGerald, 4th Earl of Desmond
John FitzGerald, 4th Earl of Desmond( died 1399) was the son of Gerald FitzGerald, 3rd Earl of Desmond.
He married and had one son, Thomas, who succeeded him as Earl of Desmond.
According to Burke, John FitzGerald married Joan Roche, the daughter of Lord Fermoy.
In March 1399 FitzGerald drowned at Ardfinnan on the River Suir, and was buried at Youghal.
He was succeeded by his son Thomas FitzJohn FitzGerald, 5th Earl of Desmond.
Maurice FitzGerald, 9th Earl of Desmond
Maurice FitzGerald, 9th Earl of Desmond( died 1520) was the brother of James FitzGerald, 8th Earl of Desmond.
Thomas FitzGerald, 7th Earl of Desmond
Thomas FitzJames FitzGerald, 7th Earl of Desmond (died 1467/68), called 'Thomas of Drogheda', and also known as the Great Earl, was the son of James FitzGerald, 6th Earl of Desmond and Mary de Burgh.
He was Lord Deputy of Ireland for the Duke of Clarence from 1463 to his death, and in 1464 founded the College of Youghal.
His plan to found a University at Drogheda failed due to his judicial assassination.
John FitzGerald, de facto 12th Earl of Desmond
John FitzGerald, de facto 12th Earl of Desmond( died December 1536) was the brother of Thomas FitzGerald, 11th Earl of Desmond.
Upon his brother's death in 1534, John disputed the title to the earldom of his brother's grandson, James FitzGerald, de jure 12th Earl of Desmond.
According to the" Annals of the Four Masters", John FitzThomas FitzGerald was believed to have instigated the murder of his older brother, James FitzGerald, 8th Earl of Desmond in 1487, and had been expelled by his brother Maurice FitzGerald, 9th Earl of Desmond.
< ref>[ https://books.google.com/books?id=DdhC3eVIdHgC&pg=PA530&dq=James+FitzGerald,+8th+Earl+of+Desmond&hl=en&sa=X&ved=0ahUKEwjDkbTshJjZAhVPrVkKHVoGDLc4FBDoAQg_MAQ#v=onepage&q=
James FitzGerald, 8th Earl of Desmond&f= false Connellan, Owen.
" The Annals of Ireland[ from A.D. 1171 to A.D. 1616", Dublin.
Brian Geraghty, 1846, p. 309]
Rudolph Feilding, 8th Earl of Denbigh
Rudolph William Basil Feilding, 8th Earl of Denbigh, 7th Earl of Desmond (9 April 1823 – 10 March 1892) was a British peer, succeeding to his titles on the death in 1865 of his father, the 7th Earl of Denbigh.
He was noted as a Roman Catholic convert, and founder of the Franciscan friary at Pantasaph, North Wales.
Donal MacCarthy Reagh
Donal MacCarthy Reagh( 1450/1460–1531) was the 12th Prince of Carbery from 1505 to his death in 1531.
He belonged to the MacCarthy Reagh dynasty, and was the son of Finghin MacCarthy Reagh, 10th Prince of Carbery, and Lady Catherine FitzGerald, daughter Thomas FitzGerald, 7th Earl of Desmond.
In some sources and pedigrees he is known as Donal( Donnell)" MacFineere" MacCarthy Reagh, although it is not known if this refers to his father or to some other aspect of his upbringing.

Question: Who is the paternal grandfather of Thomas Fitzgerald, 7Th Earl Of Desmond?
Answer: Gerald FitzGerald, 3rd Earl of Desmond