Mephistopheles

Lord of the City of Thieves, the Duke of Lies.

Mephistopheles, known most commonly as the Duke of Lies, is the Lord of Selfishness and prince of the fifth layer of The Nine Hells. His Chambers of Commerce reside in a poisonous swamp, keeping an iron grip on the precious little clean air and water in the realm. His city is a miserable dump populated by devils possessed by souls who, in life, were viciously selfish and relentless in their pursuit of comfort at the expense of others. It is one of the most dangerous layers of the Hells solely because of how cutthroat its denizens are, and how deceptive they can be. Mephistopheles, lord of them all, is the worst. 
He appears as a wolf-headed humanoid man with an elven face hidden in his jaws. His hands are mechanical and made of finely carved ivory, and he wears perfectly trim suits in muted colors. Out of all the princes of the Hells, Mephisopheles and Dispater are known as the most polite and soft-spoken, but where Dispater seeks to disengage, Mephistopheles has a hungry personality that always seeks to draw in. It is highly unusual to catch a glimpse of his second face, and even rarer to survive it, as it usually means he is angry.
Mephistopheles rules his City under the assumption that the selfish souls moving through it will eventually grind each other down to a snapping point. After a decade of being surrounded by wolves, even a wolf will realize that constantly trying to prey on others is not, in fact, a good way to live. Whether or not this works, Mephistopheles watches over his prisoners for weaknesses he can exploit himself, always hungry.