Super creepy and long lost brother of the Chestfarter.
The Lunger is packed with contagious disease. Slow but never resting, it will find you by scent.
Weak points, belly and legs. Belly will explode in a shower of contagious goo, so avoid close quarters and shotguns. Listen for dry cough, and heavy breathing.
Also if you haven't played Amnesia The Dark Decent by now, I suggest you get going. Most scary game I've played in 2010.