[Marya]

Акаллабет:
There he took up again his great Ring in Barad-dûr, and dwelt there, dark and silent, until he wrought himself a new guise, an image of malice and hatred made visible; and the Eye of Sauron the Terrible few could endure.

О Кольцах Власти:
He took up again the great Ring and clothed himself in power; and the malice of the Eye of Sauron few even of the great among Elves and Men could endure.

Интересно, что это - еще до Последнего Союза, когда Саурон еще мог принимать форму, хоть уже и не прекрасную.

После усекновения пальца:
Then Sauron was for that time vanquished, and he forsook his body, and his spirit fled far away and hid in waste places; and he took no visible shape again for many long years.

Потом Sauron took shape again, и что это за shape, мне непонятно. Око могло с тем же успехом быть просто видением в сознании тех, кто был "настроен" на Саурона.

Пиппин в Палантире видел "Его", который спрашивал взглядом.

Письмо 246:
Sauron should be thought of as very terrible. The form that he took was that of a man of more than human stature, but not gigantic. In his earlier incarnation he was able to veil his power (as Gandalf did) and could appear as a commanding figure of great strength of body and supremely royal demeanour and countenance.

Не исключено, что эта форма была ему все еще доступна и в Третью эпоху - это описание Толкина связано с ВК, Арагорном и Фродо, так что очень может быть, что он и тогда был уже воплощен.