Daniel Rankin Steuart FRSE FIC FCS (10 March 1848 – 1 August 1925) was a 19th/20th century Scottish industrial chemist.
He was born in Bogside, North Lanarkshire on 10 March 1848, the son of Sarah Whitehead (1805-1888), and her husband the elderly Alexander Steuart (1789-1865).
He then undertook postgraduate studies in Glasgow and Munich before joining the Oakbank Oil Works under George Beilby.
In 1877 he was appointed Chief Chemist of the newly created Broxburn Oil Company.
Their youngest son 2nd Lt James William Harvie Steuart served in the Royal Scots during the First World War and was severely wounded in the Battle of Arras in April 1917, eventually dying of his wounds on 12 May 1920.