| Honorific-Prefix: | The Right Honourable |
| The Lord Kilmany | |
| Honorific-Suffix: | MC PC |
| Constituency Mp: | Berwick and East Lothian |
| Term Start: | 25 October 1951 |
| Term End: | 10 March 1966 |
| Predecessor: | John Robertson |
| Successor: | John Mackintosh |
| Constituency Mp1: | North Lanarkshire |
| Term Start1: | 27 October 1931 |
| Term End1: | 15 June 1945 |
| Predecessor1: | Jennie Lee |
| Successor1: | Margaret McCrorie Herbison |
| Birth Date: | 5 March 1905 |
| Party: | Unionist |
William John St Clair Anstruther-Gray, Baron Kilmany, MC PC (5 March 1905 – 6 August 1985) was a Scottish Unionist Party politician.
The only son of Col William Anstruther-Gray of Kilmany and Clayre Jessie Tennant, he was educated at Eton College and at Christ Church, Oxford, England. He served as a Lieutenant in the Coldstream Guards from 1926 to 1930, and with the Shanghai Defence Force in 1927–28.
He was elected as Unionist Member of Parliament (MP) for North Lanarkshire, in Scotland, in 1931, holding the seat until 1945. Until September 1939, he served as Parliamentary Private Secretary to Financial Secretary to the Treasury, and to Secretary for Overseas Trade, and latterly to Sir John Colville, Secretary of State for Scotland.
In September 1939, he rejoined the Coldstream Guards and served in North Africa, France and Germany with Coldstream Guards and Lothians and Border Horse. He was promoted to the rank of Major in 1942. He was awarded the Military Cross in 1943.
He served as Assistant Postmaster-General from May–July 1945. He contested Berwick and East Lothian in February 1950, and was elected for the seat in 1951, holding it until 1966. He was Chairman of Ways and Means and Deputy Speaker of the House of Commons from 1962 to 1964 (having been Deputy Chairman from 1959 to 1962). He was Chairman of the 1922 Committee from 1964 to 1966.
He was appointed Deputy Lieutenant of Fife in 1953, and Lord Lieutenant of Fife from 1975 to 1980. He was also the Crown nominee for Scotland on the General Medical Council from 1952 to 1965.
He was created a baronet in 1956, appointed a Privy Counsellor in the 1962 Birthday Honours.
On his defeat in the 1966 election, he was created a life peer as Baron Kilmany, of Kilmany in the County of Fife. His wife died in 1985, he in August the same year aged 80.
In 1934, Anstruther-Gray married Monica Helen, only child of Geoffrey Lambton, second son of Frederick Lambton, 4th Earl of Durham.