Born June 12, 1892, in Komotini, Thrace. Figure in the Greek workers’ and Communist movements. Tobacco worker by trade.
In 1910, Gkrozos became active in the trade union movement; from 1914 to 1917 he served in the Greek Army. In 1920 he joined the Communist Party of Greece (CPG). He was elected to the leadership bodies of party organizations in Thessaloniki, Corfu, and Macedonia. From 1926 to 1935 he was secretary of the executive committee of the Greek Federation of Tobacco Workers. In 1936 he was elected a member and secretary of the executive committee of the All-Greece Federation of Tobacco Workers. He was arrested in 1937 and was in prison and exile until 1943 (he spent a total of about ten years in prisons and exile).
Gkrozos took part in the struggle against the fascist occupation. In 1945 he became a member of the Central Committee of the CPG. In 1946 he was elected secretary-general of the All-Greece Federation of Tobacco Workers and a member of the National Council of the Greek General Confederation of Labor. In 1948–49 he performed party work with the Democratic Army of Greece, and from 1948 to 1956 he was chairman of the Central Control Committee of the CPG. In March 1956 he became a member of the Politburo and, in February 1957, chairman of the Central Committee of the CPG.