Despite Russia's protests, Stalin was no less villainous than Hitler
Some do counter that Stalin was, despite his excessive toughness, a great figure in Russian and Soviet history. (Modern Russian history textbooks make the same case.) But that ignores Stalin's disastrous record as a political and military leader. His paranoia decapitated the Red Army leadership: the best generals were murdered or jailed. Also, Stalin ignored the plentiful warnings of Hitler's planned surprise attack in June 1941. That nearly proved disastrous.
By some counts Stalin should be seen as no less villainous than Hitler. He bears much of the blame for the war. It was the Soviet alliance with Hitler that gave the Nazi leader the confidence to attack Poland. Only Hitler's blunders prevented the Nazis from winning the war in the East—and quite likely the whole show. It is also worth remembering that Stalinism was so repellent that it drove many Russians to fight on the Nazi side—including in the SS.