Margaret Kennedy, Marchioness of Ailsa (1772 – 5 January 1848) was a Scottish noblewoman. She was born in 1772 to John Erskine and Mary Baird. On 1 June 1793, she married Archibald Kennedy, Lord Kennedy, who the following year succeeded as 12th Earl of Cassilis. Margaret inherited the House of Dun, a Georgian house, in 1824, and achieved the rank of Marchioness when her husband was created Marquess of Ailsa in 1831. She died on 5 January 1848.