Tony Cliff (born Yigael Gluckstein (Hebrew: ???? ??????????); 20 May 1917 – 9 April 2000) was a Trotskyist activist.
Born to a Jewish family in what is now Israel, he moved to Britain in 1947 and by the end of the 1950s had assumed the pen name of Tony Cliff.
A founding member of the Socialist Review Group, which became the International Socialists and then the Socialist Workers Party, in 1977, Cliff was effectively the leader of all three.