Goblins are a fictional sapient species in the Harry Potter universe.
Appearance and Biology
Goblins are small humanoids with dome-like heads and pointed noses and ears, long fingers and sharp nails. Many possess black irises. Goblins can interbreed with humans, producing 'half-goblins' who retain their goblin ancestors' small size.
Presumably relatives of House-Elves, Goblins were once an independant people with access to magic. However, at some unknown point prior to the 18th century, they fought a war with human wizards who eventually beat them and took away their magic wands, tragically limiting their magical abilities. Goblins, who had an affinity for metallurgy, turned to their craft as a last resource and quickly made themselves essential to wizards by creating artifacts and coins for them. Over the centuries, they rebelled many times, but their rebellions were always squashed, as they are primarily merchants and not warriors.
In recent times, all Goblins in the United Kingdom work for the Wizarding Bank, Gringotts, which both keeps money for the wizards and creates the needed coins.
Behind the scenes
In some ways, Harry Potter goblins are similar to Northern Mythology's Dwarves, as small, deformed craftsman known for their metallurgy.