Purim
There is a tale in the Hasidic Chabad movement that supposedly Joseph Stalin died as a result of some metaphysical intervention of the seventh Chabad leader, Rabbi Menachem Mendel Schneerson, during the recitation of a discourse at a public Purim Farbrengen. Stalin was suddenly paralyzed on 1 March 1953, which corresponds to Purim 1953, and died 4 days later. Due to Stalin's death, nationwide pogroms against Jews throughout the Soviet Union were averted, as Stalin's infamous doctors' plot was halted.
Bolesław Bierut
Bierut died under mysterious circumstances in Moscow on 12 March 1956 during a visit to the Soviet Union, shortly after attending the 20th Congress of the Communist Party of the Soviet Union during which Nikita Khrushchev delivered his "Secret Speech", criticizing Stalin's cult of personality. His death gave rise to speculation about poisoning or suicide.