Robertson Gladstone, JP (15 November 1805 – 23 September 1875) was an English merchant and politician. He was the second son, and third child of Sir John Gladstone and the brother of William Ewart Gladstone who was Prime Minister of the United Kingdom four times. Robertson was a successful merchant, businessman, property developer and local politician. One of the youngest men elected Mayor of Liverpool, he was religious but increasingly tolerant of nonconformity, emphasised by a move towards semi-socialist politics.