Percival Stanley Brookfield (7 August 1875 – 22 March 1921) was an Australian politician and militant trade unionist. He was variously known as Percival Jack Brookfield or Jack Brookfield, a member of the New South Wales Legislative Assembly from 1917 until his violent death in 1921. In parliament he was a member of the Labor Party (ALP) until July 1919 and then joined the Industrial Socialist Labor Party.