Baron Kilmarnock, of Kilmarnock in the County of Ayr, Scotland, is a title in the Peerage of the United Kingdom. It was created in 1831 for William Hay, 18th Earl of Erroll. This was a revival of the Kilmarnock title held by his great-grandfather William Boyd, 4th Earl of Kilmarnock, who was attainted in 1746 (with his titles forfeited). The barony of Kilmarnock remained a subsidiary title of the earldom of Erroll until the death in 1941 of the eighteenth Earl's great-great-grandson, the twenty-second Earl. The earldom, which could be passed on through female lines, was inherited by the late Earl's daughter and only child, the twenty-third Countess. The barony of Kilmarnock, which could only be passed on to male heirs, was inherited by the Earl's younger brother, the sixth Baron. He assumed the surname of Boyd in lieu of Hay the same year he succeeded to the title. As of 2013[update] the title is held by his younger son, the eighth Baron, who succeeded his elder brother in 2009.
