Aliens?

[Elmo]

After the Valar, who before were the Ainur of the Great Song, entered into Ea, those who were the noblest among them understood most of the mind of Illuvatar sought amid the measurable regions of the Beginning for that place where they should establish the Kingdom of Arda in time to come. And when they had chosen that point and region where it should be, they began the labours that were needed. Others there were, countless to our thought though known each and numbered in the mind of Illuvatar, whose labour lay elsewhere and in other regions and histories of the Great Tale, amid stars remote and worlds beyond the reach of the furthest thought. But of these we know nothing and cannot know, though the Valar of Arda, maybe, remember them all.

This quote form Myths Transformed I find very intriguing due to the mention of other worlds. This reminds me of all those worlds in the Magician's Nephew and they throw up many questions even though Tolkien says we cannot know anything about them. Is Tolkien implying that there are 'aliens' in his imaginary world? Are these beings Children of Illuvatar as well as Elves and Men? Or are there Elves and Men in these distant worlds? Perhaps even more intriguing is the fact that Melkor did not exist in these worlds as Myths Transformed mentions he concentrated all his power on Arda. Are these worlds therefore free of evil?

[Raynor]

Tulkas may be one such "alien", at least in the beginning.In the Annals of Aman, it is stated in the 1500 VY:

It came to pass that hearing afar of the war in Arda Tulkas the Strong came thither out of distant regions of Ea to the aid of Manwe.

This is consistent with the Silmarillion:

Originally Posted by Of the Valar, Valaquenta

He came last to Arda, to aid the Valar in the first battles with Melkor

Originally Posted by Of the beginning of days

But in the midst of the war a spirit of great strength and hardihood came to the aid of the Valar, hearing in the far heaven that there was battle in the Little Kingdom; and Arda was filled with the sound of his laughter.

[The Might]

No, I doubt any other Children of Illuvatar existed.
Arda was the product of the music of the Ainur, all of them produced this one world. Afterwards some of them became its rulers.
But without their music, I doubt that other sentient beings would have been created anywhere else.

[Elmo]

Hip hip hurray, I've found more stuff about aliens in Ea. Elves claim that Arda is the chief point in Ea.

These views are not mathematical or astronomical, or even biological, and so cannot be held necessarily to conflict with the theories of our physical sciences. We cannot say that there ‘must’ be elsewhere in Eä other solar systems ‘like’ Arda, still less that, if there are, they or any one of them must contain a parallel to Imbar. We cannot even say that these things are mathematically very ‘likely’. But even if the presence elsewhere in Eä of biological ‘life’ was demonstrable, it would not invalidate the Elvish view that Arda (at least while it endures) is the dramatic centre. The demonstration that there existed elsewhere Incarnates, parallel to the Children of Eru, would of course modify the picture, though not wholly invalidate it. The Elvish answer would probably be: ‘Well, that is another Tale. It is not our Tale. Eru can no doubt bring to pass more than one. Not everything is adumbrated in the Ainulindalë; or the Ainulindalë may have a wider reference than we knew: other dramas, like in kind if different in process and result, may have gone on in Eä, or may yet go on.’ But they would certainly add: ‘But they are not going on now. The drama of Arda is the present concern of Eä.’ Actually it is plainly the view of the Elvish tradition that the Drama of Arda is unique. We cannot at present assert that this is untrue.

This was found in note 2 of the Athrabeth So little green men perhaps could visit the shire.

[Sir Kohran]

This is one of the things I just love above Tolkien...he slips all these intriuing little hints in, giving you just enough to wonder about and yet keeping that great sense of mystery...what is on the world beyond the reach of our thought? What is around those ever so distant stars in the sky? We will never know...but it's nice to wonder.

[The Might]

I am not sure about this, but doesn't this text precede the Silmarillion?
If it so, I guess Tolkien had some reason for which he didn't mention this in the book itself.