Grigori Yevseevich, original name Ovsel Gershon Aronov Radomyslsky. 1883–1936, Soviet politician; chairman of the Comintern (1919–26) executed for supposed complicity in the murder of Kirov. He was the supposed author of the forged 'Zinoviev letter' urging British Communists to revolt, publication of which helped to defeat (1924) the first Labour Government