Earl of Dorset is a title that has been created at least four times in the Peerage of England.
Some of its holders have at various times also held the rank of marquess and, from 1720, duke.
William de Mohun appears as earl of Dorset or Somerset, these two shires being in early times united under a single sheriff.
[1] The last creation was in 1604 for Thomas Sackville, 1st Baron Buckhurst.
In 1720 the seventh earl was created Duke of Dorset in the Peerage of Great Britain.