| Honorific Prefix: | The Right Honourable |
| The Earl of Ranfurly | |
| Office: | Member of Parliament for Dungannon |
| Term Start: | 1818 |
| Term End: | 1830 |
| Predecessor: | George Peter Holford |
| Successor: | Hon. John James Knox |
| Office1: | Member of Parliament for County Tyrone |
| Term Start1: | 1812 |
| Term End1: | 1818 |
| Predecessor1: | Hon. Thomas Knox Sir John Stewart, Bt |
| Successor1: | Sir John Stewart, Bt William Stewart |
| Birth Name: | Thomas Knox |
| Birth Date: | 19 April 1786 |
| Alma Mater: | St John's College, Cambridge |
| Parents: | Thomas Knox, 1st Earl of Ranfurly Hon. Diana Jane Pery |
| Relations: | Edmund Pery, 1st Viscount Pery (grandfather) |
Thomas Knox, 2nd Earl of Ranfurly (19 April 1786 – 21 March 1858), styled Viscount Northland between 1831 and 1840, was an Anglo-Irish peer and politician.
Ranfurly was born on 19 April 1786. He was the eldest son of Thomas Knox, 1st Earl of Ranfurly, and the Hon. Diana Jane Pery, who were first cousins. His younger brothers, Hon. Edmund Knox, was an Admiral in the Royal Navy.
His maternal grandparents were Edmund Pery, 1st Viscount Pery and the former Elizabeth Vesey. His paternal grandparents were Thomas Knox, 1st Viscount Northland, and the Hon. Anne Vesey (a daughter of John Vesey, 1st Baron Knapton). Among his extended family were uncles, Bishop William Knox and Bishop Edmund Knox, George Knox, and Archdeacon Charles Knox.
He studied at St John's College, Cambridge.
Ranfurly was returned to Parliament as one of two representatives for County Tyrone in 1812 (succeeding his father), a seat he held until 1818. Between 1818 and 1830 he was the sole representative for Dungannon in Parliament.
He gained the courtesy title Viscount Northland when his father was elevated to the earldom of Ranfurly in 1831. In 1840 he succeeded his father in the earldom and entered the House of Lords as Baron Ranfurly. His residence was Dungannon Park in County Tyrone, Northern Ireland.[1]
In 1815, Lord Ranfurly married Mary Juliana Stuart, daughter of the Most Reverend William Stuart, Archbishop of Armagh, and the former Sophia Margaret Penn (the daughter of Thomas Penn, a son of William Penn, founder of Pennsylvania).[2] Together, they had four sons and six daughters, including:[3]
Lord Ranfurly died in March 1858, aged 71, and was succeeded in the earldom by his eldest son, Thomas. Lady Ranfurly died in July 1866.[3]
Through his daughter, Lady Mary, he was a grandfather of Major General Raymond Reade, Commandant of the Royal Military College of Canada.[7]