Robert Conquest's important book, Harvest of Sorrow (1986, Oxford University Press), tells how Lenin, and later Stalin, deliberately murdered more than ten million people by inducing an artificial famine in the Ukraine. Their cruelties knew no bounds: the Red Army even took the shovels, so that peasant children not only could not plant food, but could not bury their parents after they had starved.
Conquest opens this way: "Fifty years ago as I write these words, the Ukraine and the Ukrainian Cossack and other areas to its east—a great stretch of territory with some forty million inhabitants—was like one vast Belsen. A quarter of the rural population—men, women, and children—lay dead or dying, the rest in various stages of debilitation with no strength to bury their families or neighbors. At the same time (as at Belsen), well-fed squads of police or party officials supervised the victims."
Lenin probably believed he was helping mankind. It is doubtful whether Stalin believed in anything at all. Both were singularly effective not only at killing people, but at staying in power.
Acton tells us that all power tends to corrupt. Absolute power corrupts absolutely.
Others have not been so certain. Thomas Carlyle welcomes the hero as ruler, one whose "place is with the stars of heaven. To this man death is not a bugbear; to this man life is already as earnest and awful, and beautiful, and terrible, as death."