Thomas Knox, 1st Earl of Ranfurly (5 August 1754 – 26 April 1840), styled The Honourable Thomas Knox between 1781 and 1818 and known as The Viscount Northland between 1818 and 1831, was an Irish peer and politician.
Ranfurly was elected a member of the Irish House of Commons for Carlingford in 1776, a seat he held until 1783, and then represented Dungannon between 1783 and 1790 and Tyrone between 1790 and 1798. He was also a member of the British House of Commons for County Tyrone from 1806 to 1812. In 1818 he succeeded his father in the viscountcy of Northland, but, as this was an Irish peerage it did not entitle him to a seat in the House of Lords. However, in 1826 he was created Baron Ranfurly, of Ramphorlie in the County of Renfrew, in the Peerage of the United Kingdom, which entitled him and his successors to a seat in the upper chamber of parliament. In 1831 he was further honoured when he was made Earl of Ranfurly in the Peerage of Ireland.
Lord Ranfurly married his cousin the Honourable Diana Jane, daughter of Edmund Pery, 1st Viscount Pery and Elizabeth Vesey, in 1785. Their second son the Honourable Edmund Knox (1787–1867) was an Admiral in the Royal Navy. Lady Ranfurly died in November 1839. Lord Ranfurly only survived her by a few months and died in April 1840, aged 85. He was succeeded in his titles by his eldest son, Thomas. His brothers included bishops William Knox and Edmund Knox, George Knox , and Archdeacon Charles Knox.
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- "Irish House of Commons 1692–1800". leighrayment.com. 21 May 2009. Archived from the original on 7 June 2008. Retrieved 17 June 2009.CS1 maint: unfit URL (link)
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- "No. 18259". The London Gazette. 17 June 1826. p. 1478.
- "No. 18846". The London Gazette. 9 September 1831. p. 1834.
- Hansard 1803–2005: contributions in Parliament by the Earl of Ranfurly