Rt. Hon. Isaac Foot (23 February 1880 - 13 December 1960) was a British politician and solicitor.

Foot was educated at Hoe Grammar School and worked as a solicitor in Plymouth. With his friend Edgar Bowden, he set up the law firm, Foot and Bowden which is still in existence as of 2005. He became a member of the Liberal Party and served on Plymouth City Council and as lord mayor 1920-21.

He stood for parliament in Plymouth in November 1919 but was beaten by Nancy Astor. Foot was then elected as Member of Parliament for Bodmin in February 1922. He lost his seat in October 1924 but won again in the 1929 General Election. He held the seat until he lost again in November 1935. He became a Privy Counsellor in 1937.

Foot served as Vice President of the Methodist Conference (1937-38) and as President of the Liberal Party (1947).

Foot was married to Eva Mackintosh, daughter of Angus Mackintosh. Their sons followed Foot in public life: Dingle became a Liberal, later Labour, Member of Parliament and solicitor-general; Hugh was a senior diplomat and member of the House of Lords; John stood as a Liberal on several occasions for Parliament and became Baron Foot; and Michael became a major socialist intellectual, principal architect of the 1945 Labour Party manifesto, Member of Parliament and leader of the Labour Party in the 1980s. They also had two daughters, Margaret and Jennifer, and another son, Christopher. Hugh's son, Paul, was a prominent campaigning journalist and political activist.