Goblins
Goblins are almost universally shunned because they are almost all natural criminals, cutthroats, and killers. Every crime boss or thief master is a goblin, with very few exceptions. They are extremely thrifty, known to argue over a single silver piece, and will drop water in the desert before dropping money. Goblins have diabolical minds, and few torture devices can be named which a goblin did not think up. They are extremely smart and also have a knack for survival. Stealth comes naturally to them, and their dusky grey to green, sometimes even blue or black, skin tones make them hard to spot at night.
Goblins are not really warlike, and don't really appreciate overt combat. It's not their style. A goblin would much rather satisfy its sadistic needs through thievery or betrayal than through honorable combat.