Mordecai: Zombie Killer
Mordecai, the hunter, is a zombie killing machine. With the right build, he's right up there with Lilith in terms of zombie slaying speed but has the added bonus of getting to hang back a bit. Oh, and The Zombie Island of Dr. Ned is a great place to work on your headshots as you'll soon find out.
Whether you're using a sniper rifle, pistol or revolver, you can use the same build. It's a bit contrary to the weapon strategies in Left 4 Dead, but I prefer to wield a pistol. Your focus here isn't on damage, but on controlling enemy advances. To do that, we go straight down the rogue tree.
Put your first five points into Swift Strike. Since you're going to be relying on Bloodwing a lot here, boosting his speed and damage output is a great way to go.
The next five go right into Out For Blood. Even the best hunters get surprised at some point, and you'll be glad you have Out For Blood when you need it. And don't forget, you can call Bloodwing back early if you need a quick pick-me-up.
Arial Impact is the skill that changes the game for this brand of hunter. When maxed out, Bloodwing will daze every single enemy he strikes. Zombies are fairly slow as it is, but once you've got them dazed they're going nowhere fast. It's important to start thinking of Bloodwing less as a damage dealer and more as a utility for slowing down anything in your path. You need five points in this skill, but no more. So if you're using a class mod that enhances Arial Impact, you may only need to put a few points here.
The final five points that are mandatory for this build - afterwards, you can go down the sniper and gunslinger tree as you see fit - are in Bird of Prey. Fully maxed out, Bloodwing can attack six different targets. With a class mod, that increases to a maximum of ten.
Send Bloodwing out to daze the horde, then stand back and pop their heads off one by one. Not a bad way to go!