Physical Characteristics: Goblins are short and wiry, bloodthirsty killers. Their bodies are thin and bony, usually from a combination of poor nutrition and racial traits. Their skin is gray, black, brown, or green, and their eyes are red, gray, or black. The average goblin stands between three and four-and-a-half feet tall, and weighs from 60 to 130 pounds.
Social Attributes: Goblins are delighted by the sight of blood, and shriek with joy when indulging in the act of killing. They are known to make alliances with their cousins the hobgoblins as well as orcs, ogres, kobolds, and occasionally humans. Goblins lack the intelligence to produce much intelligent conversation, but most of their discussions relate to the next city they will raid or encampent they will overrun. Other than their violent tendencies, they also spend lots of time filling their pockets with coins, often those that don't belong to them.
Roleplaying Notes: The problem with a goblin on an adventuring crew is not why he's adventuring, but why he's with his group. Many goblins would adventure just for the thrill of killing; they wouldn't, however, drag a team of elves, humans, gnomes, and hobbits with them. So this requires a lot of creativity: think about reasons the rest of the group and your character would tolerate each other. Maybe the group needs your skills, and you need backup in case you try to bite off more than you can chew.