Left 4 Dead: The Maniac

The Maniac, mechanically, works in a similar way to The Witch. He is initially passive, but if angered, is an utterly terrifying foe. Armed with a chainsaw, his attacks are equal to that of a Witch in power.

The Maniac wanders around, moaning and blind due to constant self harming. The gashes, lack of fingers, eyes and lower jaw are all down to his insane hatred of everything. Unlike The Witch, he wanders during the day, or the night. He tends to hang around fires to keep warm, and is attracted to noise. The mumbling of infected draw him, which makes him a danger to both sides. If he wanders into an infected, he kills them out of cold blood, simply for getting in the way of his blind wanderings. The constant noises made by most special infected also attract him, which can cause problems for the infected as well.

Gunshots will attract him, but with more vigour. If you shoot at all while in his presence, he will shamble swiftly towards the origin of the gunshot. If the survivor is still there, he will attack them. On easy through to advance, this means instant incapacitation, and then swift death after that. On expert, or realism mode, instant death is all you can expect.

If you shoot him directly, then his senses go into overdrive, and he will peruse his attacker like a Witch, until they are dead. If he kills the person responsible, he will run away, flailing his chainsaw around triumphantly, which within itself is a danger to anyone nearby.

If The Maniac and The Witch are encountered together, something strange happens. The Maniac, possibly entranced by her crying, will stand over her like a guardian, and The Witch, possibly feeling safe under her guardian, will stop crying, and will sing, possibly in order to keep him from leaving. When together like this, they become stationary, but even more dangerous. Aggravate them, and the death of just the attacker won’t be enough. ALL the survivors will be targeted. Working together, they will periodically kill off every player, one at a time. The only way to stop them is to kill one of them. This causes the other to stop and mourn for their lost ally. After that, their behaviour reverts to normal.

When wandering, The theme of The Maniac sounds like: [link]

The theme becomes intensified if the Maniac is bothered by a gunshot.

If he is shot directly, he becomes enraged and his theme changes to: [link]

He isn’t playable in verses, has 1000 health, and is found as often as a Witch.

Fan Version: [link]

Trivia:
-The Maniac has cut off his thumbs, which make his hands look the one used in the L4D logo.
-Most of the ideas behind this are either nicked from Killing Floor's Skrake or [link]
-His chainsaw is based on the one from the beta, and he drops it when killed, allowing the player to wield it. It usually drops with only 25% to 75% of the gas still in it, but it NEVER runs out so long as he’s holding it.