From Paul Rymer:
Have a look at the photos I've just uploaded to Flickr at:
They are of the head of a man in Room 25 of The Louvre, maybe a recent addition. Its of very high quality, and the resemblance to Nefertiti in particular is strong; but it also reminds me of Tiye, Akhenaten and even Tutankhamun.
If this were Ay, and if as has been often proposed, Ay is the brother of Tiye and the father of Nefertiti, the resemblance to the royal house makes sense. Who else could this be? The portrait is not Akhenaten (wrong jaw shape for a start), it's too old and too different to any of the known or assumed portraits of Smenkhkare or Tutankhamun. Amenhotep III? No, this man is very different.
The only other portrait that looks somewhat like this is the depiction of Ay in the tomb of Tutankhamun - it has the same jawline (notably different than Tut's), a similar nose and distance between the nose, lips and chin.
I'm surprised this piece isn't more widely known.