Evil things done by him :
(a) Great Purge : The Great Purge or the Great Terror (Russian: Большо́й терро́р) was a campaign of political repression in the Soviet Union which occurred from 1936 to 1938. It involved a large-scale purge of the Communist Party and government officials, repression of peasants and the Red Army leadership, widespread police surveillance, suspicion of "saboteurs", "counter-revolutionaries", imprisonment, and arbitrary executions.
(b) The Polish Operation : The Polish Operation of the Soviet security service in 1937–1938 was a mass operation of the NKVD carried out in the Soviet Union against Poles (labeled by the Soviets as "agents") during the period of the Great Purge. It was ordered by the Politburo against the so-called "Polish spies" and customarily interpreted by the NKVD officials as relating to 'absolutely all Poles'.
(c) Katyn massacre : The Katyn massacre (Polish: zbrodnia katyńska, "Katyń massacre" or "Katyn crime"; Russian: Катынская резня or Russian: Катынский расстрел Katynskij reznya, "Katyn massacre") was a series of mass executions of Polishintelligentsia carried out by the NKVD ("People's Commissariat for Internal Affairs", the Soviet secret police) in April and May 1940. Though the killings took place at several places, the massacre is named after the Katyn Forest, where some of the mass graves were first discovered.
Stalin's supporters have argued the following in the interest of defending his legacy:
1#. He gave Russian women equal rights. He was the very first Russian leader to do so, despite what others claim. He included universal access to quality education and health care. Technical education was promoted and transport links across the Soviet Union were improved. Industrialization created many job opportunities. Women were given equal treatment in education and employment.
2#. He made taxes lower and lowered prices for many common goods.  Inflation in the USSR was 2.3% when he was leader, yet in the USA it was 3.5%.
3#. Although Stalin was brought into the war against Nazi Germany unwillingly, the USSR led by Stalin did more than any other country to defeat the Nazi power.
4#. He saved Russia from becoming a backwater station for Nazi Germany when the Germans invaded Russia, thus saving the entire Russian race from enslavement or genocide.