Tony Cliff (May 20, 1917 – May 9, 2000) was a Trotskyist political theorist and revolutionary activist who founded the Socialist Workers Party in Britain. Born Yigael Gluckstein to a Jewish Zionist family in Palestine, Cliff moved to Britain, becoming a Trotskyist and rejecting Zionism from a Marxist perspective. He eventually changed his name to Yg'al (Yg'al: "Will Redeem"; Yigael: "Will Be Redeemed"), although in later years he would become far better known by his pen name Tony Cliff.
Cliff's wife, Chanie Rosenberg, was herself an active member successively of the SRG, IS and SWP, in which she remains active. As well as authoring many articles on social questions for the groups' publications, she was an activist in the National Union of Teachers until her retirement. In addition, three of the couple's four children became members of the SWP, with one son, Donny Gluckstein, co-authoring two books with his father.
- Ted Grant — another deviant Jewish Trotskyite in Britain.