Sir William Rae, 3rd Baronet (14 April 1769 – 19 October 1842),^[1] was a Scottish politician and lawyer.

He was born at Old Assembly Close off the Royal Mile in Edinburgh, son of Margaret Stewart, youngest daughter of John Stewart of Blairhall and David Rae, Lord Eskgrove.^[2] He was educated at the High School in Edinburgh and studied law at the University of Edinburgh from 1785, qualifying as an advocate in 1791.

His first major role was as Sheriff of Orkney and Shetland in 1801, but in 1809 he transferred to an equivalent post as Sheriff of Edinburgh, which he held until 1819.^[3] He succeeded his father to the baronetcy in 1815.

He was Member of Parliament for Anstruther Burghs, in Fife, from 1819 to 1826, Harwich, Essex, England, from 1827 to 1830, Buteshire in 1830 and from 1833 to 1842, and for Portarlington, Queen's County, Ireland, from 1831 to 1832.

He served as Lord Advocate from 1819 to 1830 and from 1834 to 1835. In the aftermath of the Peterloo Massacre, he reported to the Home Secretary, Viscount Sidmouth, on radical unrest in Scotland.^[4] He was made a Privy Councillor on 19 July 1830.^[1]

Grant's Old and New Edinburgh tells us that he was present at the Great Edinburgh Fire of 1824, actively trying to extinguish the flames of the building on the Royal Mile at the head of Old Assembly Close as it was "the house of his birth".^[5]

He died aged 73 at St Catherines, near Mortonhall in south Edinburgh on 18 October 1842.^[3]

He is buried with his father and mother on the south-west corner of St Michael's church in Inveresk. The stone is modest.

In 1793 he married Mary Stuart.

• Lee, Sidney, ed. (1896). "Rae, William (1769-1842)" . Dictionary of National Biography. Vol. 47. London: Smith, Elder & Co.