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.
George Thicknesse, 19th Baron Audley
George Thicknesse, later Thicknesse-Touchet, 19th Baron Audley (4 February 1758 – 24 August 1818) was an English peer.
George Thicknesse-Touchet was the son of Captain Philip Thicknesse and Lady Elizabeth Tuchet, daughter of James Tuchet, 6th Earl of Castlehaven.
Upon the deaths of his mother's two brothers, the Earldom became extinct, but the barony passed in the female line.
He gained the rank of Ensign in the 2nd (The Queen's Royal) Regiment of Foot.
He married, Elizabeth Delaval, daughter of Sir John Hussey Delaval, 1st Baron Delaval of Seaton Delaval and Susannah Robinson, on 21 May 1781 in Hanover Square, Mayfair, London, England.
Later he married Augusta Henrietta Catherina Boisdaune, daughter of Rev. André Boisdaune and Elizabeth Strode, on 2 May 1792.
Thicknesse-Touchet died in Sandridge Lodge, near Melksham, Wiltshire and was buried in Melksham.
He was succeeded by his only son, George Thicknesse-Touchet (1783–1837).
James Tuchet, 7th Earl of Castlehaven
James Tuchet, 7th Earl of Castlehaven( 15 April 1723 – 6 May 1769) was the son of James Tuchet, 6th Earl of Castlehaven and his wife, née Elizabeth Arundell.
He succeeded his father as Earl of Castlehaven and Baron Audley on 12 October 1740.
He was unmarried, and succeeded on his death in 1769 by his brother, John.
He was a Christian Earl who owned much land and donated parts of the proceeds to the church.
Mervyn Tuchet, 4th Earl of Castlehaven
Mervyn Tuchet, 4th Earl of Castlehaven( died 2 November 1686) was the third son of Mervyn Tuchet, 2nd Earl of Castlehaven, and his first wife, Elizabeth Barnham( 1592 – c. 1622).
He married Mary Talbot( buried 15 March 1710/ 1), daughter of John Talbot, 10th Earl of Shrewsbury( bef. 1601 – 1654) and his wife, née Mary Fortesque.
They had at least three children:
He succeeded his brother James as Earl of Castlehaven on 11 October 1684.
He also held the lower titles 14th Baron Audley and 2nd Baron Audley of Hely.
On his death, his titles passed to his son James.
John Butler (Irish Confederate)
Colonel John Butler was an officer of the Irish Confederate Army of the 1640s during the War of the Three Kingdoms.
He was the younger brother of Richard Butler, 3rd Viscount Mountgarret and part of the powerful Butler family of the Munster-Leinster border area.
Of Old English descent, like most of the family he was a Roman Catholic.
Butler took part in the unsuccessful 1644 Ulster Campaign as part of the Ulster Army under the command of James Tuchet, 3rd Earl of Castlehaven and Owen Roe O'Neill.
He was a cousin of James Butler, 1st Duke of Ormonde, the Lord Lieutenant and commander of the Royalist Irish Army.
John Tuchet, 8th Earl of Castlehaven
John Talbot Tuchet, 8th Earl of Castlehaven( 2 August 1724 – 22 April 1777) was the son of James Tuchet, 6th Earl of Castlehaven, and his wife, née Elizabeth Arundell.
He succeeded his brother as Earl of Castlehaven and Baron Audley on 6 May 1769.
He died unmarried, at which time the Earldom of Castlehaven and two of its subsidiary titles( Baron Audley of Orier and Baron Audley of Hely) became extinct as the Irish earldom and baronies were entailed honours.
The Barony of Audley created by writ of 1312 is deemed to have devolved upon his nephew, namely George Thicknesse( later Thicknesse- Touchet).
George was the son of his sister Elizabeth, who had married Philip Thicknesse
James Tuchet, 3rd Earl of Castlehaven
James Tuchet, 3rd Earl of Castlehaven( c. 1617 – 11 October 1684) was the son of Mervyn Tuchet, 2nd Earl of Castlehaven and his first wife, Elizabeth Barnham( 1592 – c. 1622).
Castlehaven played a prominent role in the Wars of the Three Kingdoms that took place in the middle of the 17th century, and was particularly active in the conflicts in Ireland at this time.
James Tuchet, 6th Earl of Castlehaven
James Tuchet, 6th Earl of Castlehaven (died 12 October 1740) was the son of James Tuchet, 5th Earl of Castlehaven and his wife Anne Pelson.
He succeeded his father as Earl of Castlehaven and Baron Audley on 9 August 1700.
He married, on 14 May 1722, Elizabeth Arundell (1693–1743), daughter of Henry Arundell, 5th Baron Arundell of Wardour and his wife, née Elizabeth Panton.
They had two sons, and at least one daughter:
He is buried at the church of St. Sulpice in Paris, France.
James Tuchet, 7th Baron Audley
James Tuchet, 7th Baron Audley( c. 1463 – 28 June 1497) was a leading rebel in the 1st Cornish Rebellion of 1497 opposing the rule of Henry VII of England.
James Tuchet was born in Heleigh Castle, Staffordshire to John Tuchet, 6th Baron Audley and Anne Echingham.
He was sentenced for treason and beheaded with the defeat of the Cornish Rebellion of 1497.
James Tuchet, 5th Earl of Castlehaven
James Tuchet, 5th Earl of Castlehaven (died 12 August 1700) was the son of Mervyn Tuchet, 4th Earl of Castlehaven and Mary Talbot.
He succeeded his father as Earl of Castlehaven on 2 November 1686.
He married Anne Pelson, daughter of Richard Pelson and his wife, née Anne Villiers, daughter of Christopher Villiers, 1st Earl of Anglesey.
They had one son, James, who succeeded him as Earl of Castlehaven.
He died of apoplexy.
His gravestone is in the floor of the south aisle of the retrochoir at Winchester Cathedral.

Question: Who is James Tuchet, 6Th Earl Of Castlehaven's paternal grandfather?
Answer: Mervyn Tuchet, 4th Earl of Castlehaven