The Islington East by-election, 1931 was a parliamentary by-election held on 19 February 1931 for the British House of Commons constituency of Islington East in Islington, North London.
The seat had become vacant when the constituency's Labour Member of Parliament (MP), Dr Ethel Bentham, died on 19 January 1931, aged 70. She had held the seat since the 1929 general election.
Labour selected as its candidate the 45-year-old Leah Manning, President of the National Union of Teachers. The Conservative Party candidate was Thelma Cazalet, a 31-year-old feminist and member of the London County Council. The Liberal candidate was Horace Crawfurd, who had been the MP for Walthamstow West from 1924 to until his defeat at the 1929 general election.
The fourth candidate, Alfred Critchley, was referred to by Thelma Cazalet as "the Beaverbrook candidate". He stood for the Empire Free Trade Crusade and the United Empire Party, which both sought to make the British Empire a free trade bloc. The Empire Crusade had won the Paddington South by-election in October 1930, and hoped to repeat its success. Critchley had been the Conservative candidate in Manchester Gorton in 1929.