The Earldom of Ranfurly, created 1831, is the last earldom created in the Peerage of Ireland that is still extant. The Earl is also Viscount Northland (created 1791) and Baron Welles (1781) in the Peerage of Ireland, and Baron Ranfurly (1826) in the Peerage of the United Kingdom.

Viscounts Northland (1791)

• Thomas Knox, 1st Viscount Northland (1729-1818), elected a Representative Peer in 1800
• Thomas Knox, 2nd Viscount Northland (1754-1840) (became Earl of Ranfurly in 1831)

Earls of Ranfurly (1831)

• Thomas Knox, 1st Earl of Ranfurly (1754-1840)
• Thomas Knox, 2nd Earl of Ranfurly (1786-1858)
• Thomas Knox, 3rd Earl of Ranfurly (1816-1858)
• Thomas Granville Henry Stuart Knox, 4th Earl of Ranfurly (1849-1875)
• Uchter John Mark Knox, 5th Earl of Ranfurly (1856-1933)
• Thomas Daniel Knox, 6th Earl of Ranfurly (1913-1988)
• Gerald Francoys Needham Knox, 7th Earl of Ranfurly (b. 1929)