Many attributes of goblins (gold hoarding, small, hook nosed) are also attributed to Jews by anti-Semitic people. My question is whether those stereotypes influenced traditional folklore about goblins or whether it's a coincidence. Thank you!
I should probably be quiet and let /u/itsallfolklore answer this, because I have the privilege and honor to be drawing massively on his fantastic research (and am of course worried I'm Doing It Wrong)...hopefully he'll come along and write something better!
In "Knockers, Knackers, and Ghosts: Immigrant Folklore in the Western Mines," he discusses how the European origins came to understand the goblins of the mines as the ghosts of dead Jews, sentenced (in properly medieval anti-Jewish fashion) to perpetual restlessness for their supposed role in the crucifixion of Jesus. And yet, this strand is woven into a rich tapestry of existing other lore:
Most of the Cornish sources suggest that the Knockers were believed to be the spirits of Jews who worked in the Cornish mines long ago. Local tradition maintains that Jews worked in Cornish mines during the Middle Ages, but there is little historical basis for this belief...There is little variation in the traditions surrounding the Jewish origin of the Knockers, which seems to be the predominant folk explanation.
[...]
The Jewish origin attributed to the Knockers should not mask the fact that they act like and are assumed to be underground elves of a sort. Throughout Europe, people once commonly maintained that the local supernatural beings were spirits of long-dead people...The Tommyknockers can be understood as underground elves who attracted the array of legends and beliefs associated with ancient Jewish miners.
A similar intermixture occures in non-folklore takes on goblins, specifically, in 18th-19th century Gothic literature that recalls the Middle Ages "through the looking class." Goblins, sometimes a generic term for humanoid creatures (dwarves, orcs, ghosts etc) and sometimes a particular, might play the role in medievalist supernatural fiction that stereotypical Jews played in medievalist conceptions of the natural Middle Ages. Dickens' Daniel Quilp; the goblin miners (yes, miners again) of MacDonald's The Princess and the Goblin and The Princess and Curdie stories; and especially the switching between goblin and Jew in G.K. Chesteron's work all illustrate this fluidity. These goblins are, generally, rather more villainous than the dangerously helpful/helpfully dangerous knockers in the Cornish mining tradition, too.
But just as harmful anti-Semitic stereotypes of Jews sometimes align with the emotional/cultural needs that folkloric and literary goblins serve, sometimes the association breaks abruptly. Returning to /u/itsallfolklore's wonderful article (truly, please go look it up if you have JSTOR access or sign up for free JSTOR access to get it), when Tommyknockers crossed the Atlantic something changed:
The idea of exiled Roman Jews was historically impossible in the New World, and Americans have seldom welcomed the belief in elves. As a result, the Cornish immigrants did not talk of Jewish spirits...The belief in ghosts, however, persisted in America, and so the notion of the Knockers as the shades of dead miners became popular in the mines of the West.
The principal difference between the European and American expression of this folklore lies in what the Tommyknockers did to or for the miners. In Cornwall, most legends tell of the Knockers rewarding good and punishing evil...The underlying moral of the Cornish tradition is that a miner who is willing to accept a moderate income and who is not too ambitious or inquisitive is worthy of reward. American culture, however, reinforces ambition, creativity and curiosity. The Cornish type of legend telling of miners rewarded for following sounds without question and then taking only a portion of the wealth did not survive in America. American folklore cannot condemn a miner's desire to take everything.
The American version of knockers discarded the explicitly Jewish basis because it could not make logical sense--but it also discarded the stereotypical basis because American culture itself celebrated what had started off as the negative stance against which the folk defined themselves. So we can see that supernatural creatures in folklore and literature serve some of the same purposes that ethnic stereotypes do--a place in the imagination, not reality, that people use to understand themselves, their world, and their history.
Go Read:
You might also be interested in a question I asked about whether folklore about dwarfs was associated with Jews.
As /u/sunagainstgold does here, /u/itsallfolklore talks a lot about Knockers, but also more broadly about creatures of folklore, and says:
we can say that aside from the Cornish example of the mining knocker, no other supernatural being – dwarf or otherwise – was considered to have Jewish attributes.
/u/AncientHistory also talks on that page about other explanations for the phenomenon of "night-daemons".