[Gothmog]

About Ungoliant:

The Eldar know not whence she came; but some have said that in ages long before she descended from the darkness that lies about Arda, when Melkor first looked down in envy upon the Kingdom of Manwe, and that in the beginning she was one of those that he corrupted to his service. But she had disowned her Master, desiring to be mistree of her own lust, taking all things to herself to feed her emptiness...

I don't think Ungoliant was some sort of creator, maybe even before Eru. Even if she existed in the Void before Arda, it doesn't mean she was equal or as old as Iluvatar. Ainur, creations of Eru's will, existed before Arda. The quote used by Bethberry:

a sound arose of endless interchanging melodies woven in harmony that passed beyond hearing into the depths and into the heights, and the places of the dwelling of Iluvatar were filled to overflowing, and the music and the echo of the music went out into the Void, and it was not void. ... 'Therefore I say: Ea! Let these things Be! And I will sent forth into the Void the Flame Imperishable, and it shall be at the heart of the World, and the World shall Be; and those of you that will may go down into it.' ...

Speaks of events after the singing of Ainur. There's no hint of the creation of the Void or what might have been before Eru made the Ainur in the Silmarillion. The first sentence for example is:

There was Eru, the One, who in Arda is called Ilúvatar; and he made the first Ainur, the Holy Ones, that were the offspring of his thoughts, and they were with him before aught else was made.

Eru is pictured as eternal, a being existing long before time itself. And it says literary that nothing else existed before he created Ainur. Ungoliant could have lived in the Void before the creation of the world, but this doesn't imply that she wasn't created by Eru. Melkor often wandered in the void places seeking the Imperishable Flame. But could a monster like Ungoliant be a creation of Eru and why? If so, was she created at the time of the Ainur, maybe even as an Ainu? Corrupted Ainu is no new occurrence, and they had the ability to take whatever shape they wanted.

Ungoliant as a revolting Ainu who didn't participate in the singing and dwelt in the Void before the creation of Arda but AFTER Eru created the Ainur looks to me like the most likely explanation. Or have I missed any suggestions of her existing before Ainur?