Stalin and Hitler planned the war together (by dividing all the Eastern European nations between the two of them - check the "Secret Protocol of the Molotov-Ribbentrop Pact"). They roughly launched the war together, by BOTH attacking Poland in September 1939, and the only major difference between those two lunatics was the fact that one of them wasn't merely wicked to the core, but also a brainless tool who got played by the other.
But for sure, Stalin should be "honoured" in all kinds of criminology and psychology textbooks as the perfect historical example of a psychopath.