Did Tom Bombadil have a “prior art” in Norse/other mythology?

Question

We know that Tolkien heavily borrowed ideas from Norse and other mythologies, since Middle-Earth was meant to be the missing myths for England.

Was there a figure similar to Tom Bombadil in Norse or any other myths that Tolkien was using as basis for his work?

Similar meaning - old (oldest) creature, odd and somewhat OUTSIDE the normal pantheon, deliberately vague as to who and what it is. Impervious to supernatural evil (Tom is immune to the Ring) but doesn't fight it.

Please note that Tolkien apparently state that Tom!=Eru in the letters, so "top level world creator living in disguise" figures don't seem to match.

Answer 1

Not that I'm aware of, but Tom was in origin not a part of the Middle-earth mythology. Rather he was a character that existed already (originally published in the Oxford Magazine in 1933 or 34), and - in Tolkien's own words (Letter 153):

In historical fact I put him in because I had already 'invented' him independently (he first appeared in the Oxford Magazine) and wanted an 'adventure' on the way.

Because of that I don't think it's valid to go looking for parallels to him in other mythologies, at least in the context of inspiration for Middle-earth. Tom serves a different purpose in the story (Letter 153 again):

I kept him in, and as he was, because he represents certain things otherwise left out.

And also (Letter 19):

Tom Bombadil, the spirit of the (vanishing) Oxford and Berkshire countryside...

I'll leave the final words to the Professor himself (Letter 229):

As for Wayland Smith being a Pan-type, or being reflected both in Bombadil and in Gollum: this is sufficient example of the silly methods and nonsensical conclusions of Dr. O. He is welcome to the rubbish, but I do not see that he, as a translator, has any right to unload it here.