In fairy tales, goblins are mischievous, magical creatures. While fairies and gnomes are often portrayed as kind, goblins are usually malicious troublemakers.
In the 1500s, a goblin was defined as "a mischievous and ugly fairy" or "a devil." Since then some fictional goblins have been slightly less menacing than that original definition suggests, but these mean little creatures are almost never the heroes of the stories in which they appear. In the Harry Potter books, dangerous goblins control the wizard banks, and the Spiderman films include several malevolent goblins among their antagonists.