Julian Leszczyński
Julian Leszczyński (; 8 January 1899 in Płock – 20 August 1939), also known by pseudonym Leński, was leader of the Stalinist faction in the Communist Party of Poland (KPP), led the party in the 1930s, and himself fell victim to the Great Purge.

He joined the Social Democracy of the Kingdom of Poland and Lithuania in 1905, and was also a member of the Bolshevik Party.  From 1917 he was a commissar of the Polish Commissariat of the Russian People's Commissariat for Nationalities, and a member of the Polish Bureau of the Bolshevik Party Central Committee.  He was on the Central Committee of the KPP (1925–37), the Politburo (1927–37) and was General Secretary from 1929–37.  From 1926 he was on the executive of the Communist International and from 1929 was a member of its Presidium.

In mid-June 1937 he was summoned by the Comintern from Paris to Moscow and arrested by the NKVD.  There is some doubt about whether he was executed immediately or not.  According to one version of events, he was imprisoned and died on 20 August 1939.