The Kings of Ireland have twice created the Earldom of Antrim in the Peerage of Ireland. The first creation occurred in 1620 for Randal Macdonnell. The first Earl's successor received the title of Marquess of Antrim in 1645, but he died without heirs, so the Marquessate became extinct.
In the late eighteenth century the earldom seemed in danger of extinction, with only one surviving male heir of the first Earl surviving. The Sovereign, therefore, created a new Earldom of Antrim in 1785 in favour of the sixth earl, with a special "remainder" that allowed the title to pass to his daughters. In 1789 the Sovereign also created the sixth Earl "Marquess of Antrim", without special remainder. When the sixth earl died in 1791, the original earldom and the Marquessate became extinct while the newer earldom passed to his daughter Anne. After her death, the earldom passed to her sister Charlotte. Since her death only males have held the earldom.
Randal MacDonnell, 1st Marquess of Antrim (1609 - February 3, 1683), was a landed magnate in Scotland and Ireland son of the 1st Earl of Antrim, was educated as a Roman Catholic.
Antrim subsequently returned to Oxford and being sent by the king in 1645 with letters for the queen at St Germains.
Antrim is described by Clarendon as "of handsome appearance but of excessive pride and vanity and of a marvellous weak and narrow understanding." He married secondly Rose, daughter of Sir Henry O'Neill, but had no children, being succeeded in the earldom by his brother Alexander, 3rd earl of Antrim.