David Douglas, Lord Reston was a Scottish judge and the heir of Adam Smith.

He was born on 24 July 1769, in Strathendry, the fifth and youngest son of Col. Robert Douglas of Strathendry (1716–1803) and Cicilia Craigie, daughter of Robert Craigie, Lord President of the Court of Session.

He attended Edinburgh High School (with Sir Walter Scott), 1777–1782, and Glasgow University, where he studied under Millar. It is set down in the History of the Speculative Society that he read a paper there on 30 November 1790 on "The Effects of Taxation on the Necessaries of Life." Advocate 1791, Sheriff-Depute of Berwickshire 1809. Lord of Session 1813. Lord of Justiciary, as Lord Reston, 1816. Fellow of the Royal Society of Edinburgh 27 Jan 1817. Senator of the Royal College of Justice. He died at Glendoick on 23 April 1819.

He spent his later childhood with Adam Smith, who was a first cousin of his father, and received Smith's property, including his library, on his death.

He married Elizabeth Craigie, his first cousin, in 1805 and had four children:

David Douglas (25 June 1799 – 12 July 1834) was a Scottish botanist. He born to John Douglas, a stonemason and Jean Drummond. He worked as a gardener, and explored the Scottish Highlands, North America, and Hawaii, where he died.

The son of a stonemason, he was born in the village of Scone north-east of Perth, Scotland. He attended Kinnoull School and upon leaving he found work as an apprentice to William Beattie, head gardener at the estate of the 3rd Earl of Mansfield at Scone Palace. He spent seven years at this position, completing his apprenticeship, and then spent a winter at a college in Perth to learn more of the scientific and mathematical aspects of plant culture. After a further spell of working in Fife (during which time he had access to a library of botanical and zoological books) he moved to the Botanical Gardens of Glasgow University and attended botany lectures at the University of Glasgow. William Jackson Hooker, who was Garden Director and Professor of Botany, was greatly impressed with him and took him on an expedition to the Highlands before recommending him to the Royal Horticultural Society of London.

David (Hebrew: דָּוִד, דָּוִיד, Modern David Tiberian Dāwîḏ; ISO 259-3 Dawid; Strong's Daveed; beloved; Arabic: داوود‎ or داود‎ Dāwūd) was, according to the Hebrew Bible, the second king of the United Kingdom of Israel and, according to the Gospel of Matthew and the Gospel of Luke, an ancestor of Jesus. David is seen as a major Prophet in Islamic traditions. His life is conventionally dated to c. 1040–970 BC, his reign over Judah c. 1010–1003 BC,^{[citation needed]} and his reign over the United Kingdom of Israel c. 1003–970 BC.^{[citation needed]} The Books of Samuel, 1 Kings, and 1 Chronicles are the only sources of information on David, although the Tel Dan stele records "House of David", which some take as confirmation of the existence in the mid-9th century BC of a Judean royal dynasty called the "House of David".

David is very important to Jewish, Christian and Islamic doctrine and culture. In Judaism, David, or David HaMelekh, is the King of Israel, and the Jewish people. Jewish tradition maintains that a direct descendant of David will be the Messiah. In Islam, he is known as Dawud, considered to be a prophet and the king of a nation. He is depicted as a righteous king, though not without faults, as well as an acclaimed warrior, musician, and poet, traditionally credited for composing many of the psalms contained in the Book of Psalms.