The title of Marquess of Londonderry is a title in the Peerage of Ireland created in 1816 for Robert Stewart, 1st Earl of Londonderry, father of Lord Castlereagh, the Foreign Secretary at the time.
The Marquess holds the subsidiary titles of Earl of Londonderry (Irish, 1796), Earl Vane (Peerage of the United Kingdom, 1823), Viscount Castlereagh (Irish, 1795), Viscount Seaham (U.K., 1823), Baron Londonderry (Irish, 1789), and Baron Stewart of Stewart's Court (U.K. 1814).
Between 1823 and 1999, the Marquess sat in the House of Lords as Earl Vane. For a year prior to that, he sat as Baron Stewart of Stewart's Court
Marquesses of Londonderry (1816)
- Robert Stewart, 1st Marquess of Londonderry (1739-1821)
- Robert Stewart, 2nd Marquess of Londonderry (1769-1822)
- Charles William Stewart, later Vane, 3rd Marquess of Londonderry (1778-1854)
- Frederick William Robert Stewart, 4th Marquess of Londonderry (1805-1872)
- George Henry Robert Vane-Tempest, 5th Marquess of Londonderry (1821-1884)
- Charles Stewart Vane-Tempest-Stewart, 6th Marquess of Londonderry (1852-1915)
- Charles Stewart Henry Vane-Tempest-Stewart, 7th Marquess of Londonderry (1878-1949)
- Edward Charles Stewart Vane-Tempest-Stewart, 8th Marquess of Londonderry (1902-1955)
- Alexander Charles Robert Vane-Temptest-Stewart, 9th Marquess of Londonderry (b. 1937)
