Monster Monday: What creature is this?

Today, I have decided to try an exercise with the audience. As the hobby has grown, most "staple" monsters are well known by players and game masters alike. If I say "walking into the massive cavern, you are surrounded by life-like statues. The medusa must be near." everyone (relatively speaking) knows exactly what a medusa is, and how to combat it. With that in mind, I have chosen a monster that is fairly common at mid-levels. If I mentioned its name, you would know immediately what you were facing and how to confront it. Instead, I am going to give a description, and see what the readers think it is.

The Setting:
The adventurers had been contracted by a city to look into the disappearance of some less influential citizens. Most were homeless, but one had been a lesser noble's son who had been on a drinking bender in the slums. The trail led the group to an old mansion at the top of a bluff. After finding some grisly remains in some closets and hidden rooms, the party has made their way to the basement.

Coming down the stairs, the party sees the following creature:

A dirty humanoid is there, with crazy hair. His fingers are elongated, with sharp claws at the fingertips. His clothes are ripped and threadbare. Through the openings in his shirt, you can see his skin, paper thin and pasty white. He stands there, smiling a visage of needle-like teeth. His dull eyes seem to have a malevolent red tinge, but do not reflect the light of your torches as a living being's would.

Can you tell me what kind of creature it is?