Patrick Ruthven, 1st Earl of Forth
Patrick Ruthven, 1st Earl of Forth and 1st Earl of Brentford( c. 1573 – 2 February 1651) was a Scottish nobleman, general, and diplomat.
Alan, 1st Earl of Richmond
Alan, 1st Earl of Richmond (before 1100 – 15 September 1146), Breton "Alan Penteur", also known as "Alan the Black", was a Breton noble who fought for Stephen, King of England.
Alan was the third son of Stephen, Count of Tréguier, and Hawise de Guingamp.
Constance of Penthièvre
Constance of Penthièvre( c. 1140 – after 23 June 1184) was a Breton princess, daughter of Alan of Penthièvre, 1st Earl of Richmond, and Bertha of Cornouaille," suo jure" Duchess of Brittany.
Thomas Pitt
Thomas" Diamond" Pitt( 5 July 1653 – 28 April 1726) of Stratford in Wiltshire and of Boconnoc in Cornwall, was an English merchant involved in trade with India who served as President of Madras and six times as a Member of Parliament.
He was the grandfather of William Pitt, 1st Earl of Chatham(" Pitt the Elder") and was great- grandfather of Pitt the Younger, both prime ministers of Great Britain.
Robert Stewart, 1st Earl of March
Robert Stewart, 1st Earl of Lennox then 1st Earl of March( c. 152229 March 1586) was a Scottish nobleman of the family of Stewart of Darnley.
Stephen, Count of Tréguier
Stephen of Penthièvre, Count of Tréguier, 3rd Lord of Richmond (1058/62 – 21 April 1136) was a Breton noble and a younger son of Odo, Count of Penthièvre and Agnes of Cornouaille, sister of Hoël II, Duke of Brittany.
In 1093, he succeeded to the title of Count of Tréguier; in 1098, he succeeded his brother Alain as Lord of Richmond in Yorkshire, England.
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.
James Bathe
James Bathe( c.1500–1570) was an Irish judge of the Tudor era, who was notable for serving as Chief Baron of the Irish Exchequer for thirty years under four successive monarchs.
He was the grandfather of the 1st Earl of Roscommon, and of the noted musician William Bathe.
Gilbert Talbot, 3rd Baron Talbot
Gilbert Talbot, 3rd Baron Talbot( c. 1332–1387) was an English nobleman and soldier.
He was the grandfather of John Talbot, 1st Earl of Shrewsbury.
Thomas Boleyn, 1st Earl of Wiltshire
Thomas Boleyn, 1st Earl of Wiltshire, 1st Earl of Ormond, 1st Viscount Rochford( c. 1477 – 12 March 1539), of Hever Castle in Kent, was an English diplomat and politician who was the father of Anne Boleyn, Queen Consort and the second wife of King Henry VIII, and was thus the maternal grandfather of Queen Elizabeth I of England.

Question: Who is Alan, 1St Earl Of Richmond's paternal grandfather?
Answer: Odo, Count of Penthièvre