The word "Goblin" comes from the French word, "Gobelin."  This was the name of a nasty local spirit that troubled a town in Normandy, a province in France.  The name came to England sometime in the 14th Century. 

There is another kind of goblin.  It's called a "hobgoblin."  It's a friendlier sort of goblin.  It doesn't do much harm.  It prefers pranks.