James Hay, 15th Earl of Erroll (20 April 1726–3 July 1778) was the son of William Boyd, 4th Earl of Kilmarnock.

He was born with the name of James Boyd but legally changed it to James Hay in 1758, when he succeeded his great-aunt as Earl of Erroll (his father's titles were attainted and thus he did not succeed to them).

In 1762, he married Isabella Carr and they had four children:

• Augusta Hay (d. 1822)
• George Hay, 16th Earl of Erroll (1767–1798)
• William Hay, 17th Earl of Erroll (1772–1819)
• Lady Margaret Hay (c. 1778–?)

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