Isaac Foot (23 February 1880 – 13 December 1960) was a British Liberal politician and solicitor.

Isaac Foot was born in Plymouth, the son of a carpenter and undertaker who was also named Isaac Foot, and educated at Plymouth Public School and the Hoe Grammar School, which he left at the age of 14. He then worked at the Admiralty in London, but returned to Plymouth to train as a solicitor. Foot qualified in 1902, and in 1903, with his friend Edgar Bowden, he set up the law firm Foot and Bowden, which as Foot-Anstey still exists.

He became a member of the Liberal Party, and in 1907 was elected to Plymouth City Council, of which he remained a member for twenty years, serving as Deputy Mayor in 1920. As Deputy Mayor he represented Plymouth in the United States for the celebrations of the Mayflower's tercentenary.

Foot first stood for parliament in Totnes in January 1910, losing to the sitting Liberal Unionist, F. B. Mildmay He then stood twice for Bodmin, but was unsuccessful. At Plymouth Sutton in the by-election of November 1919 he was beaten by Nancy Astor, who became the first woman MP in Britain to take her seat in Parliament and a lifelong friend of Foot.

Foot was elected as Member of Parliament for Bodmin at a by-election in February 1922, retaining his seat in the general elections of 1922 and 1923. He lost his seat in October 1924 but regained it in the 1929 general election, when the Liberals took all five Cornish seats. He held the seat until he lost again in the 1935 general election.

Foot served on the Round Table Conference on India in 1930–31 and on Burma in 1931 and was also on the Joint Select committee on India. His championing of the poor of the subcontinent earnt him the sobriquet of "the member for the Depressed Classes".

In 1931 he became Secretary for Mines in the National Government, but resigned the following year in protest at the protectionist Ottawa Agreements.

He fought two more elections, at St Ives in 1937, and Tavistock in 1945, losing both.