Goblins exist as far as two million years ago and were responsible for imprisoning a Djinni in a mythic cup. They, however, were forced into hiding along with the rest of the magical community because of the human fear of magic.
Goblins have green skin, very little hair and lizard-like tails. Some goblins can have blue skin and don't possess tails.
Later on, goblins were seen to be purple, with long and pointy noses. They wore short sleeve shirts and pants, no shoes, have sharp teeth, big eye brows, and their lizard tails look like iguana tails.
Life in the magical world
Goblins seem to be the worst scum of the magical world, often finding themselves in illicit deals, even with the Huntsclan, a organization bent on rid the Earth of all magical creatures. Though the Leprechauns also make deals with them, they possess some code of ethic on what exactly they sell, especially if the goods could destroy all magical creatures. Goblins, in the other hand, posses no such code.
Goblins have a keen sense of smell to sniff out where the Oracles are, smell and running when danger is approaching, and sniff out a creature that is captured.