What animals in Animal Farm symbolize certain leaders like Joseph Stalin,Czar Nicholas, Nikolai Lenin&more?

Out of the all of the animals in Animal Farm like Snowball, Napeolean, Boxer, Old Major, Moses, Benjamin, Muriel, Mr. Jones, Jessie and Bluebell, Minimus, which animals symbolize people like Nikolai Lenin, Joseph Stalin, Czar Nicholas IL., Leon Trotsky and Karl Marx? ANy help is apprecitaed and thanks so much!