What about Stalin? The man was already noted as dangerous by Lenin (before he took power) because of his mental instability and extremist views of Marxism. As soon as he came to power, Stalin purged factories, the army, everything. All because he saw them as potential opponents.
Stalin had no extreme view of Marxism...In fact, he could have cared less about Marxism...He cared only for power, pure & simple...Stalin was extremely paranoid, and his paranoia knew no bounds...However, the story of Stalin has an interesting twist due to this: Stalin was rumoured to have a Jewish Father (Djugasvilli is sometimes translated as the 'jew's son')...BUT, Stalin was extremely wary of the Jews, as they were the authors of the worst communist atrocities...They made up about 95% of the Bolshevik 'elite' when Stalin came to power...So, Stalin used them in various ways,
sometimes as his henchmen, but sometimes as the target of his paranoia...He also covered his bases by having two Jewish wives...But, in the end, after WWII, Stalin's 'Jewish Paranoia' got the best of him, and after the state of Israel was established, Stalin decided that Jews in the Soviet Union had dual loyalties, and was reported to have been planning a large 'pogrom' of Jews, and their resettlement in Siberia...The direct stimulus for this was Stalin getting wind of Jewish plans for a 'second Israel', which would have involved areas of the Ukraine and Moldova, with the 'capital' in Odessa...This was when Stalin reported the famous 'Doctor's Plot' against him...Shortly afterwards he was murdered by a Jewish 'triad' of Beria, Kaganovitch & Krushchev.