Conservative estimates say nearly 700,000 people were executed in Stalins Great Terror of 1937-38. The Memorial rights group keeps a database with records of some 3 million victims of Soviet repression.
700K isn't an estimate, it's a joke. Memoriale may have a database of 3 million, but their estimate runs to 40 million (not all died in the gulag system, some were merely executed in Lubyanka, or other prisons, or just got arrested on the street, or out of thir homes in the middle of the night, and never were seen again. Thanks CondoleezzaProtege.
Add those victims of the Holodomor too.