Here, I'll go get the list of new zombies I thought of a long time ago.

Leecher - Pretty average, except when it kills someone it gets large amounts of HP back. As fast as a human with knockback the same as the Classic. This would replace the Classic class.

Breaker - Very slow, more than a deformed probably. This tall guy has the special ability of being able to push barricades just by slamming himself into them. Imagine a vending machine being thrown at another vending machine. He may look menacing, but he's also the easiest to kill due to his skinny exterior, which allows bullets to easily hit his important internal organs.

Flamer - Constantly on fire (though it does not effect vision as much), so obviously it is immune to fire. Faster than a human, yet slower than a Predator. Has low knockback. This would replace the Infected class, simply because it would be awesome.