I'm not sure why you're looking for the .class file. If you have a development environment then you can view the source directly and find the villager class at net.minecraft.entity.passive.EntityVillager and the enderman class at net.minecraft.entity.monster.EntityEnderman.
And has it been the same since beta 1.9? If not, how was it called?
Or the name of the enderman's? (same questions)
I'm not sure why you're looking for the .class file. If you have a development environment then you can view the source directly and find the villager class at net.minecraft.entity.passive.EntityVillager and the enderman class at net.minecraft.entity.monster.EntityEnderman.
If you haven't already, you should have a look at MCP and use that.