Geoffrey Denis Erskine Russell, 4th Baron Ampthill (15 October 1921 – 23 April 2011), was a British hereditary peer and businessman, whose paternity and succession to the peerage were disputed in the "Ampthill baby case".
His father, John Russell, 3rd Baron Ampthill, had petitioned to disclaim paternity whilst divorcing Russell's mother, Christabel Hulme Hart, in 1923, claiming non-consummation. The petition was rejected on appeal and Russell's mother was granted a declaration that he was legitimate.
Educated at Stowe School, Russell served in the Irish Guards during the Second World War, being commissioned as a captain in 1941. He served with the Guards Armoured Division in France in 1944, where he was wounded, and in Norway in 1945.
In 1946, Ampthill married Susan Winn, a granddaughter of the 2nd Baron St Oswald and of the 1st Baron Queenborough, whom he divorced in 1971; they had three sons and a daughter. He then married Elisabeth Mallon in 1972, divorcing her in 1987. He was succeeded in the title by his first-born son David Russell.