I believe this evidence is rather conclusive - credits to
http://tolkien.slimy...html#SauronForm from where I c&ped.
There is strong evidence that Sauron did have a humanoid physical body at the time of LotR. In "The Black Gate is Closed"
we read, "'He has only four [fingers] on the Black Hand, but they are enough', said Gollum shuddering." Gollum was tortured
in Barad-dur, and this statement sounds as if it comes from personal experience. Some have objected that Gollum's memory
of his torture might not be accurate for various reasons, but this is still the only fully "canonical" evidence on either side of the
issue, so it should be taken seriously.
It need not be taken alone, however. Tolkien makes multiple unambiguous statements that Sauron did have a physical form
in Letters. For example, he describes Sauron's use of a humanoid shape in Letter #200:
It is mythologically supposed that when this shape was 'real', that is a physical actuality in the physical world and not a
vision transferred from mind to mind, it took some time to build up. It was then destructible like other physical
organisms. ... After the battle with Gilgalad and Elendil, Sauron took a long while to re-build, longer than he had done
after the Downfall of Numenor (I suppose because each building-up used up some of the inherent energy of the spirit...)
Because it took time for Sauron to "re-build" after his body was slain by Gil-galad and Elendil, it is clear that it was more
than just a "vision". Another clear statement can be found near the end of Letter #246, where Tolkien discusses the possibility
of a direct confrontation between Sauron and a Ring-wielder at the end of the Third Age (he considers both Aragorn and Gandalf).
He says,
in a tale which allows the incarnation of great spirits in a physical and destructible form their power must be far greater when
actually physically present. ... The form that he took was that of a man of more than human stature, but not gigantic.
No statements by Tolkien conflicting with these descriptions are known.
Some have objected that the many references to the "Eye" of Sauron must refer to his physical shape. However, Tolkien used
that term even when referring to the period before the war of the Last Alliance, when it is well known that Sauron had a
physical form: for example, the Akallabeth says that after Sauron "came back to Middle-earth and to Mordor... the Eye of
Sauron the Terrible few could endure."
So what does "the Eye" refer to if not Sauron's physical form? Frodo's perception of it is described in "The Passage of the Marshes":
But far more he was troubled by the Eye: so he called it to himself. ... The Eye: that horrible growing sense of a hostile will that
strove with great power to pierce all shadows of cloud, and earth, and flesh, and to see you: to pin you under its deadly gaze, naked, immovable.
A very similar comment about Morgoth appears in Text X of the "Myths Transformed" section of Morgoth's Ring:
...Morgoth held the Orcs in dire thraldom; for in their corruption they had lost almost all possibility of resisting the domination
of his will. So great indeed did its pressure upon them become ere Angband fell that, if he turned his thought towards them,
they were conscious of his 'eye' wherever they might be.
We know with absolute certainty that Morgoth had a huge but humanoid physical form during the First Age, so "eye" here
obviously refers to his will. The similarity between this description and the many references to Sauron's "Eye" is striking,
which seems to make the meaning of that term clear.
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Credits to
http://tolkien.slimy...html#SauronForm