John Cochrane, 4th Earl of Dundonald

John Cochrane, 4th Earl of Dundonald (4 July 1687 – 5 June 1720), was a Scottish aristocrat and politician.

Early life Cochrane was born on 4 July 1687. He was the second son of John Cochrane, 2nd Earl of Dundonald and Lady Susan Hamilton. His elder brother was William Cochrane, 3rd Earl of Dundonald, who did not marry.

His paternal grandparents were William Cochrane, Lord Cochrane (eldest son and heir apparent of William Cochrane, 1st Earl of Dundonald) and the former Lady Katherine Kennedy (a daughter of John Kennedy, 6th Earl of Cassilis). His maternal grandparents were William Hamilton, Duke of Hamilton and Anne Hamilton, suo jure Duchess of Hamilton.

He entered the University of Glasgow at age 14. William Cochrane, 5th Earl of Dundonald (1708–1725), who died unmarried. Lady Catherine Cochrane (d. 1786), who married, as his second wife, her cousin Alexander Stewart, 6th Earl of Galloway, in 1729.

After the death of his first wife, he married Mary Somerset, Duchess of Beaufort (1688–) on 15 October 1715. Mary, the widow of Henry Somerset, 2nd Duke of Beaufort, was the youngest daughter of Peregrine Osborne, 2nd Duke of Leeds and the former Bridget Hyde (only daughter and heiress of Sir Thomas Hyde, 2nd Baronet, of Aldbury).

Lord Dundonald died on 5 June 1720 before reaching age 33. He was succeeded in his titles by his only son, William. His widow died in Scotland in .