John Kennedy, 6th Earl of Cassilis
John Kennedy, 6th Earl of Cassilis, PC( d. April 1668) was a Scottish peer, the grandson of Gilbert Kennedy, 4th Earl of Cassilis, and nephew of John Kennedy, 5th Earl of Cassilis.
He succeeded to the titles of 8th Lord Kennedy and 6th Earl of Cassilis on 25 July 1616.
He was a non-sitting member of Cromwell's House of Lords, and was invested as a Privy Counsellor of Scotland on 13 February 1660/ 61.
He held the office of Justice- general 1649- 1651 and of an Extraordinary Lord of Session for Scotland June 1661- July 1662.
John Kennedy, 8th Earl of Cassilis
John Kennedy, 8th Earl of Cassilis( April 1700 – 7 August 1759) was a Scottish peer.
He succeeded to the titles of 10th Lord Kennedy and 8th Earl of Cassilis on 23 July 1701.
He held the office of Governor of Dumbarton Castle between 1737 and 1759.
On the death of the 8th Earl, a competition arose, both for the estates and for the title of Earl of Cassilis, between William, Earl of March and Ruglen, heir general, and Sir Thomas Kennedy of Culzean, 4th Baronet, the heir male.
The Court of Session found the right to the estates to be in the latter, 29 February 1760; and the same was found with regard to the title on a reference to the House of Lords, 27 January 1762.
Archibald Kennedy, 4th Marquess of Ailsa
Archibald Kennedy, 4th Marquess of Ailsa, DL, JP, FSRGS( 22 May 1872 – 27 February 1943), styled Earl of Cassilis until 1938, was a Scottish peer, barrister and soldier.
David Kennedy, 1st Earl of Cassilis
David Kennedy, 3rd Lord Kennedy and 1st Earl of Cassilis( 1463 – 9 September 1513) was a Scottish peer, the son of John Kennedy, 2nd Lord Kennedy.
He was born about 1463, Maybole, Ayrshire, Scotland.
He was a Privy Councillor of King James IV and was created Earl of Cassilis by him in 1502.
Ralph Neville, 3rd Earl of Westmorland
Ralph Neville, 3rd Earl of Westmorland( c. 1456 – 6 February 1499) was an English peer.
He was the grandfather of Ralph Neville, 4th Earl of Westmorland.
John Kennedy, 5th Earl of Cassilis
John Kennedy, 5th Earl of Cassilis (1575 – 14 November 1615) was a Scottish peer, the son of Gilbert Kennedy, 4th Earl of Cassilis.
He succeeded to the titles of 7th Lord Kennedy and 5th Earl of Cassillis on 14 December 1576.
In 1596 Kennedy travelled in France and Italy and wrote to Archibald Douglas from Venice.
He was one of the central figures in "The Historie Of The Kennedyis", an anonymous account of the feud between the Cassilis and Bargany Kennedy families published in 1830 by Robert Pitcairn.
This feud climaxed in a pitched battle in December 1601, in which the Earl's men fatally wounded the Laird of Bargany who was returning home from Ayr.
According to the Historie, the Earl also summarily hung a young man named Dalrymple, to whom he was related, for being a closer relation of Bargany's.
In most these deeds he was heavily influenced by his Tutor Laird Thomas Kennedy of Culzean, which led to the murder of Culzean, by Bargany's younger brother, Thomas Kennedy of Drummurchie at Greenan Castle on 12 May 1602.
He held the office of Treasurer of Scotland on 22 March 1598/99.
Gilbert Kennedy, 3rd Earl of Cassilis
Gilbert Kennedy, 3rd Earl of Cassilis  (12 May 1515 – 15 November 1558) was Scottish landowner, soldier, politician and judge.
He served as Treasurer of Scotland.
The son of Gilbert Kennedy, 2nd Earl of Cassilis, he succeeded to the titles of 5th Lord Kennedy and 3rd Earl of Cassillis in August 1527.
On 6 February 1540/41 he had a charter of the Fief of Cassilis.
As a young man, Kennedy studied at the University of St. Andrews and in Paris under the Scottish humanist George Buchanan for five years.
In November, 1542, Kennedy, in his late twenties at the time, was taken prisoner at the Battle of Solway Moss, and after a short stint in the Tower of London, was placed under the care of Thomas Cranmer, Archbishop of Canterbury.
Scottish historian Gilbert Burnet (1643-1715) believed that it was this relationship with Cranmer that led Kennedy toward Protestantism,
as certainly he was one of the first of the Scottish nobility to adopt Reformed views.
However, since his time with Cranmer lasted only one month, it is likely that his earlier contact with Buchanan had been a stronger influence in this regard.
Sir Thomas Wharton, Warden of the English West March, wrote to the Privy Council of King Henry VIII, on the tenth of December 1542, regarding ransoms for prisoners taken at the battle, including the Earl of Cassilis, who was taken by Batill Routlege.
Credit was also given to John Musgrave who "claimeth a part for the loan of his horse to the said Routlege."
Cassilis held the office of Treasurer of Scotland in 1554, of Extraordinary Lord of Session between 1546 and 1558.
He fought in the Battle of Pinkie Cleugh on 10 September 1547.
In 1558 he was present, as one of the eight Commissioners appointed by the Scottish Parliament, at the marriage of Mary, Queen of Scots, to the Dauphin of France, to whom the Scottish deputies unanimously refused the Crown matrimonial.
The Court of France appeared deeply mortified by this disappointment, and the Earl of Cassilis, with two others of the Commissioners, dying in one night, on 28 November 1558, at Dieppe, a report was raised that they had been poisoned, which was further countenanced by the death of a fourth Commissioner, Lord Fleming, at Paris, on 16 December 1558.
However, according to the Dictionary of National Biography, this report was untrue, as the actual dates of death of these persons were not the same, Cassilis dying in November.
Henry II of France had appointed Gilbert as Gentleman in Ordinary of his Chamber on 4 May 1558, and this honour was transferred to his heir, Gilbert, 4th Earl of Cassilis on 10 February 1559.
Gilbert Kennedy, 4th Earl of Cassilis
Gilbert Kennedy, 4th Earl of Cassilis, PC (c. 1541–14 December 1576) was a Scottish peer, the son of Gilbert Kennedy, 3rd Earl of Cassilis.
He succeeded to the titles of 6th Lord Kennedy and 4th Earl of Cassillis on 28 November 1558.
He fought in the Battle of Langside on 13 May 1568, for the side of Mary, Queen of Scots.
He married Margaret Lyon, daughter of John Lyon, 7th Lord Glamis; and became a Protestant after his marriage.
They had two legitimate children.
Cassilis was known as the "King of Carrick" for the feudal influence he possessed in that region.
Cassilis died in 1576 after falling from his horse.
Gilbert Kennedy, 2nd Earl of Cassilis
Gilbert Kennedy, 2nd Earl of Cassillis( died between 24 and 30 August 1527) was a Scottish nobleman, the son of David Kennedy, 1st Earl of Cassilis and Agnes, daughter of William Borthwick, 3rd Lord Borthwick.
He was married to Lady Isabel Campbell, daughter of Archibald Campbell, 2nd Earl Argyll and Elizabeth Stewart.
Children of Gilbert Kennedy, 2nd Earl of Cassillis and Lady Isabel Campbell:
David Kennedy, 10th Earl of Cassilis
David Kennedy, 10th Earl of Cassilis( bef. 1734 – 18 December 1792), was a Scottish peer, the third son of Sir John Kennedy, 2nd Baronet by Jean Douglas.
He succeeded to the titles of 10th Earl of Cassilis, 12th Lord Kennedy and 5th Baronet Kennedy on 30 November 1775 on the death of his elder brother Thomas, the 9th Earl, who had died without male issue.
He held the office of representative peer of Scotland from 1776 to 1790.
It was the 10th Earl who ordered the rebuilding of Culzean Castle on the Ayrshire coast.
Lord Cassilis never married, and the baronetcy became extinct on his death; the other titles passed to a distant cousin, Archibald Kennedy, 11th Earl of Cassilis, who lived in New York.

Question: Who is the paternal grandfather of Gilbert Kennedy, 4Th Earl Of Cassilis?
Answer: Gilbert Kennedy, 2nd Earl of Cassilis