Goblins

Goblins are members of the Fey world, but are the very bottom rung of Fey society. its not so much that they were allowed to stay, its that they didn't care enough to round them ALL up when they left.
Goblins sometimes kidnap children, to make changelings of them for the greatest Fey. It hasn't occurred to the goblins that this might cause some strife with Humans, who do not obey the desires of the Great Fey. Nor does it occur to them disobey they great fey. The goblins are not slaves, but have served the will of the great fey for so long that doing other wise feels odd and perverse to them.

The favorite food of goblins is mutton, which reminds them of a sheep like creature that lived on the greenskins home plane. ( the name of which roughly translates to Home)

If a tribe of goblins are VERY hungry they might raid a Human encampment and steal anything they feel they can eat or use, or is just too pretty to pass on. Sometimes they take human children just because they are pretty, these children are treated relatively well. And are cared for in the best way that goblins know to care for a human child. (which is sometimes quite poorly, and others they guess based on how elven children are treated)