First we have to decide what the message of Animal Farm is. I believe the theme of the novel is that power corrupts and absolute power corrupts absolutely.
While Stalin and Trotsky were the "poster children" of this idea through their brutal treatment of their "comrades" after the overthrow of Czar Nicholas (they became as corrupt as the government they overthrew), the concept can be applied to most any government or authoritarian leader where the power they have achieved goes to their heads and they become corrupted.
A good example might be Sadam Hussein. In 1968 he was a leader of the coup that put the Ba'ath party in power. Eventually he became president and slowly took control of most aspects of Iraqi society. His lust for power and the riches that come with it had him living in a palace surrounded with opulence, while most of his people languished and were brutally held down.