Tolkien has had a profound impact on the way we percieve fantasy settings, and through them, our intuitive understanding of mythology and folklore. One of the most notable differences between pre- and post-Tolkien fantasy is the tendency to give certain mythical creatures physical forms.
For example, the Kobold, Gnome and Goblin are all different words for the same creature, the creature known in my native language as "nisse", and which is known by different names in other European languages, at least in the Germanic and Celtic cultural areas. This creature also shares a lot of qualities with the norse dwarfs, and may be decended from them.
More notably, however, than the tendency to use different names for the same creature as names for different creatures (a practice most common in RPGs, as there is a constant demand for new monsters in such settings), is the tendency to give these creatures physical form. In folklore, all those creatures listed above where spirits, able to take physical form, but not really being native to that form. I think the idea of Dwarves, Goblins and Elves as predominately physical creatures stems from the way they are portrayed in Tolkiens litterature.
At least I can't think of any fantasy stories prior to Tolkien portraying them in such a way. The protagonists are mainly human, and antagonists are usually other humans or more or less mindless monsters.