Character Analysis
Moe Greene (Alex Rocco) is a casino magnate, a gangster who fashions himself as a self-made man even though he actually attained his success largely with help from the Corleones. He makes the mistake of refusing the kind of offer you can't refuse (and of smacking Fredo Corleone around): This results in a bullet to the eye (which just kind of smashes the lens of his glasses in the movie), a death sentence for poor Moe.
But, hey—the dude was threatening to turn tail and side with Don Barzini, the main rival of the Corleones. And Michael couldn't let that happen.