James Hay, Lord Hay and Lord Slains (c.1797 – 16 June 1815) was a British aristocrat and soldier. James Hay was the son of William Hay, 17th Earl of Erroll and his wife Alicia Eliot (d. 1812). Hay, an ensign in the 1st Foot Guards, was killed at the Battle of Quatre Bras while serving as aide-de-camp to General Maitland. Had he lived, he would have succeeded his father as Earl of Erroll upon his death in 1819; as it was, his brother William who succeeded to that title.