Tom Bombadil

[obloquy]

Maia, as no enigmas were mentioned as being in the halls of Iluvatar during the making of Arda, nor of any being made by him.

Ungoliant was anomalous and somewhat enigmatic. Not nearly as popular as Tom, but I think probably of a similar nature. She's an example that not everything in Arda was designated to be there.

Bombadil was a Maia who came to Arda to aid the Valar as they prepared it for the awakening of the Children of Iluvatar.

This kind of statement may be fine when you're debating with people who know you have no explicit evidence to back up your assertion, but please don't confuse the Tolkien novices.