The Earldom of Kellie was united with the Earldom of Mar in 1835, when the 26th Earl of Mar became also the 11th Earl of Kellie. At the death of that Earl in 1866, the Earldom of Kellie and the family's estates passed to Walter Erskine, the cousin of the late Earl, and his heir-male. Meanwhile, it was assumed that the Earldom of Mar passed to John Francis Goodeve, the late Earl's nephew, and his heir-general. Goodeve changed his name to Goodeve Erskine; his claim was agreed upon by most individuals. He even participated in the election of Scottish representative peers for the Peerage of Scotland.
However, the Earl of Kellie submitted a petition to the House of Lords asking that the Earldom of Mar be declared his, dying before it could be considered. His son, the 13th Earl of Kellie, renewed the petition, and the Lords decided the matter in 1875, determining that the Earldom of Mar properly belonged to the Earl of Kellie. However, due to a sentiment that the Lords had decided wrongly, the Earldom of Mar Restitution Act was passed. That Act declared that there were two Earldoms of Mar — one that would belong to the Earl of Kellie, and another that would belong to John Goodeve Erskine.
The subsidiary titles belonging to the Earl of Mar and Kellie are: Viscount of Fentoun or Fenton (created 1606), Lord Erskine (1429) and Lord Erskine of Dirleton (1603), the former of which is used as a courtesy title for the eldest son and heir of the Earl. Both titles are in the Peerage of Scotland. The Earl is Hereditary Keeper of Stirling Castle.
Sir Thomas Erskine (1566–1639), 1st Earl of Kellie, 1st Viscount Fentoun, 1st Lord Erskine of Dirleton
Thomas Erskine (d. 1643), 2nd Earl of Kellie, 2nd Viscount Fentoun, 2nd Lord Erskine of Dirleton (predecessor's grandson)
Alexander Erskine (d. 1677), 3rd Earl of Kellie, 3rd Viscount Fentoun, 3rd Lord Erskine of Dirleton (predecessor's brother)
Alexander Erskine (d. 1710), 4th Earl of Kellie, 4th Viscount Fentoun, 4th Lord Erskine of Dirleton
Alexander Erskine (d. 1756), 5th Earl of Kellie, 5th Viscount Fentoun, 5th Lord Erskine of Dirleton
Thomas Alexander Erskine (1732–1781), 6th Earl of Kellie, 6th Viscount Fentoun, 6th Lord Erskine of Dirleton (predecessor's son)
Archibald Erskine (1736–1795), 7th Earl of Kellie, 7th Viscount Fentoun, 7th Lord Erskine of Dirleton (predecessor's brother)
Charles Erskine (1765–1799), 8th Earl of Kellie, 8th Viscount Fentoun, 8th Lord Erskine of Dirleton (predecessor's third cousin once removed). In 1791 he succeeded to the Erskine of Cambo Baronetcy which merged with the Earldom until its extinction in 1829.
Thomas Erskine (c. 1745–1828), 9th Earl of Kellie, 9th Viscount Fentoun, 9th Lord Erskine of Dirleton (predecessor's brother)
Methven Erskine (c. 1750–1829), 10th Earl of Kellie, 10th Viscount Fentoun, 10th Lord Erskine of Dirleton (predecessor's uncle)
John Francis Miller Erskine (1795–1866), 11th Earl of Kellie, 11th Viscount Fentoun, 11th Lord Erskine of Dirleton (succeeded to Earldom of Kellie 1829, confirmed 9th/26th Earl of Mar 1835)
Walter Coningsby Erskine (1810–1872), 12th Earl of Kellie, 12th Viscount Fentoun, 12th Lord Erskine of Dirleton (recognized posthumously as 10th Earl of Mar)
Walter Henry Erskine (1839–1888), 13th Earl of Kellie, 13th Viscount Fentoun, 13th Lord Erskine of Dirleton (predecessor's son). Recognised 11th Earl of Mar 1875)
Walter John Francis Erskine (1865–1955), 12th Earl of Mar, 14th Earl of Kellie, 14th Viscount Fentoun, 14th Lord Erskine of Dirleton (predecessor's son)
John Francis Hervey Erskine (1921–1993), 13th Earl of Mar, 15th Earl of Kellie, 15th Viscount Fentoun, 15th Lord Erskine of Dirleton (predecessor's grandson)
James Thorne Erskine (b. 1949), 14th Earl of Mar, 16th Earl of Kellie, 16th Viscount Fentoun, 16th Lord Erskine of Dirleton, 16th Lord Erskine of Dirleton, Baron Erskine of Alloa Tower (life peer)
Thomas Erskine (1736–1797) 9th Earl of Kellie, 9th Viscount of Fentoun (1606 & 1619), 9th Baron Erskine of Dirletowne, 9th Lord Dirletoun, 9th Baronet Erskine of Cambo
Methven Erskine (1736–1797) 10th Earl of Kellie, 10th Viscount of Fentoun (1606 & 1619), 10th Baron Erskine of Dirletowne, 10th Lord Dirletoun, 9th Baronet Erskine of Cambo
Baronetcy Erskine of Cambo extinct, 1797
John Thomas Erskine (1772–1828) 25th Earl of Mar (1st creation), 8th Earl of Mar (7th creation)
Charles Erskine (1732–1781) 8th Earl of Kellie, 8th Viscount of Fentoun (1606 & 1619), 8th Baron Erskine of Dirletowne, 8th Lord Dirletoun, 8th Baronet Erskine of Cambo
John Francis Miller Erskine (1795–1866) 26th Earl of Mar (1st creation), 9th Earl of Mar (7th creation), 11th Earl of Kellie, 11th Viscount of Fentoun (1606 & 1619), 11th Baron Erskine of Dirletowne, 11th Lord Dirletoun
Frances Jemima Goodeve (d. 1842)
Walter Coningsby Erskine (1810–1872) 10th Earl of Mar (7th creation), 12th Earl of Kellie, 12th Viscount of Fentoun (1606 & 1619), 12th Baron Erskine of Dirletowne, 12th Lord Dirletoun
Frances Jemima Goodeve (1831–1887)
John Francis Erskine Goodeve-Erskine (1836–1930) 27th Earl of Mar (1st creation)
Walter Henry Erskine (1839–1888) 11th Earl of Mar (7th creation), 13th Earl of Kellie, 13th Viscount of Fentoun (1606 & 1619), 13th Baron Erskine of Dirletowne, 13th Lord Dirletoun
Alice Young (1858–1951)
Charles Walter Young (1862–1898)
John Francis Hamilton Sinclair Cunliffe Brookes Forbes Goodeve-Erskine (1868–1932) 28th Earl of Mar (1st creation)
Walter John Francis Erskine (1865–1955) 12th Earl of Mar (7th creation), 14th Earl of Kellie, 14th Viscount of Fentoun (1606 & 1619), 14th Baron Erskine of Dirletowne, 14th Lord Dirletoun
Charles Macdonald Lane (1882–1956)
Lionel Walter Erskine-Young (1891–1965) 29th Earl of Mar (1st creation)
John Francis Hervey Erskine (1921–1993) 13th Earl of Mar (7th creation), 15th Earl of Kellie, 15th Viscount of Fentoun (1606 & 1619), 15th Baron Erskine of Dirletowne, 15th Lord Dirletoun
James Thorne Erskine (b. 1949) 14th Earl of Mar (7th creation), 16th Earl of Kellie, 16th Viscount of Fentoun (1606 & 1619), 16th Baron Erskine of Dirletowne, 16th Lord Dirletoun