Old Major: Some argument exists over who he represents. Some critics believe that he is Karl Marx, the creator of Marxism, but most believe that Old Major is Lenin, the leader of Russia's Bolshevik Revolution. He preceded Josef Stalin.
Napoleon: He represents Josef Stalin--Russia's dictator who followed Lenin. While some of Lenin's goals might have been well-intentioned, Stalin did not even try to demonstrate good will. Like Napoleon in the novel, he rules with an iron fist and eliminates all who question or rebel against him.
Snowball: He represents Trotsky, head of Lenin's propaganda machine. Stalin disagreed with Trotsky and ran him out of Russia. Many believe that Stalin had Trotsky killed after he fled Russia.