Alexander Leslie FRSE PRSSA (16 September 1844 – 7 December 1893) was a Scottish civil engineer.
He was born in Dundee on 16 September 1844 the son of the civil engineer James Leslie and his wife Jane Hunter (1804-1887).
He then briefly gained extra experience as a land surveyor with a Mr Macbey of Elgin before joining the firm of Morkle & Prodham working on the Blaydon and Conside Railway.
In 1882 he was elected a Fellow of the Royal Society of Edinburgh his proposers being Thomas Stevenson and Peter Guthrie Tait.
Robert had earlier been a school friend and probably through this connection met his sister, Charlotte Leslie (1846–1935).