A Nameless Thing? An embodiment of darkness? An evil spirit? A maia? A vala?? An alien???
There are quite a few things that Tolkien left enshrouded in mystery, and the true nature of Ungoliant is one of them. But there are hints, and we can follow those hints as we try to better our understanding and form some theories.
Before we dive into what Ungoliant is, here is a brief exposition of who she is: Ungoliantë (Quenya for "Gloomweaver, Shadow Spider"), better known by her Sindarised name Ungoliant (the proper Sindarin form being Delduthling), was a gigantic spider-creature that dwelt in Avathar - a dark strip of land at the feet of the Pelóri Mountains in south-eastern Aman, shadowed from the light of the Two Trees in Valinor. Ungoliant would later help Melkor destroy the Two Trees, casting the world into darkness. Following Melkor to Beleriand she demanded the Silmarils for herself, and would've overpowered Melkor if the Balrogs had not come to his aid and driven Ungoliant away. It is said that she ended up devouring herself in her endless hunger - but before she did, at some point, she also spawned Shelob.
In older versions of the legendarium, as seen in the Book of Lost Tales (Part 1), Ungoliant had several other names: Ungwë Lianti, Ungweliant, Gwerlum [the Black], Gungliont, Ungoliont and Móru.
Móru, back in this early version of the tale, is said to be the 'Primeval Night' that is personified in the form of a great spider. In this version Tolkien even goes on to speculate about Ungwë Lianti's origin:
However, the more well known (and far more relevant) version of the story is the one we see in the published Silmarillion:
Here we can note some remarkable changes from the original version: now it is the Eldar who "knew not whence she came", rather than the Valar; and we are also told that perhaps* in the past she was in the service of Melkor.
(*) I say 'perhaps' because of the wording "but some have said..." - intentional ambiguity on Tolkien's part.
Unfortunately, however, this still does not answer the question sufficiently. So we must dig deeper.
Now turning to look at the Later Quenta Silmarillion - the more mature form of the tales told in the published Silmarillion, which in many cases (or perhaps indeed in all cases) reflects Tolkien's conception of the legendarium more accurately. In Morgoth's Ring we see two more versions of the text:
The various versions are similar yet different. It appears that Tolkien's latest conception, though still very vague, views Ungoliant as a creature that came from the "Outer Darkness", and very probably a servant of Melkor, at one point, who then went rogue and left his service to live in Avathar, where he would later find her and re-enlist her aid. It is suggested, however, that the Valar had no knowledge of her, which complicates the picture. It does however seem clear that Ungoliant is quite different in her nature from the Nameless Things, at the very least.
From here we enter the realm of speculation, and there can be a great many ways to interpret the quotes above. Indeed it can even be interpreted that Ungoliant was some kind of alien! But my opinion is somewhat different.
There is an interesting passage in the Ainulindalë, that caught my eye some time ago:
Thus the Valar and the Maiar were in fact only some of the Ainur, whereas the rest of them decided to remain with Eru outside of Eä.
Therefore it can even be theorised that Ungoliant was in fact an Ainu and was "one of those that [Melkor] had corrupted to his service". The Valar's ignorance of her can perhaps be explained in that they did not know what she had become, or perhaps they did not even know that she entered Eä to begin with - for it is said that she "had descended from the darkness that lies about Arda, when Melkor first looked down in envy upon the light in the kingdom of Manwë", and thus (within the scope of this theory) would not have been one of the Ainur that entered Eä at first, but rather decided to enter it later. By this reasoning, it may even be argued that Ungoliant, had she joined the Ainur who entered Eä originally rather than entering it later, might have been counted among the Valar herself - her ability to overpower Melkor, though 'fuelled' at the time by the power of the Two Trees that she had consumed, is a remarkable feat.
To clarify - Ungoliant is not a Vala. She is probably not a Maia either. And if we are to be perfectly honest, we really don't know what she is, and that is fun aspect of it... But perhaps, had her story been slightly different, she may have been a Vala (or at least a Maia); it is an interesting prospect, though speculative as it is.
Go on. Crucify me.
There are quite a few things that Tolkien left enshrouded in mystery, and the true nature of Ungoliant is one of them. But there are hints, and we can follow those hints as we try to better our understanding and form some theories.
Before we dive into what Ungoliant is, here is a brief exposition of who she is: Ungoliantë (Quenya for "Gloomweaver, Shadow Spider"), better known by her Sindarised name Ungoliant (the proper Sindarin form being Delduthling), was a gigantic spider-creature that dwelt in Avathar - a dark strip of land at the feet of the Pelóri Mountains in south-eastern Aman, shadowed from the light of the Two Trees in Valinor. Ungoliant would later help Melkor destroy the Two Trees, casting the world into darkness. Following Melkor to Beleriand she demanded the Silmarils for herself, and would've overpowered Melkor if the Balrogs had not come to his aid and driven Ungoliant away. It is said that she ended up devouring herself in her endless hunger - but before she did, at some point, she also spawned Shelob.
In older versions of the legendarium, as seen in the Book of Lost Tales (Part 1), Ungoliant had several other names: Ungwë Lianti, Ungweliant, Gwerlum [the Black], Gungliont, Ungoliont and Móru.
Móru, back in this early version of the tale, is said to be the 'Primeval Night' that is personified in the form of a great spider. In this version Tolkien even goes on to speculate about Ungwë Lianti's origin:
(The Book of Lost Tales: Part I, "The Theft of Melko", p. 167)
However, the more well known (and far more relevant) version of the story is the one we see in the published Silmarillion:
(The Silmarillion, "Of the Darkening of Valinor")
Here we can note some remarkable changes from the original version: now it is the Eldar who "knew not whence she came", rather than the Valar; and we are also told that perhaps* in the past she was in the service of Melkor.
(*) I say 'perhaps' because of the wording "but some have said..." - intentional ambiguity on Tolkien's part.
Unfortunately, however, this still does not answer the question sufficiently. So we must dig deeper.
Now turning to look at the Later Quenta Silmarillion - the more mature form of the tales told in the published Silmarillion, which in many cases (or perhaps indeed in all cases) reflects Tolkien's conception of the legendarium more accurately. In Morgoth's Ring we see two more versions of the text:
(Morgoth's Ring, "The Annals of Aman", 1492; p.98: §105)
(§106)
(Morgoth's Ring, "The Later Quenta Silmarillion", "(I) The First Phase: (6) Of the Silmarils and the Darkening of Valinor"; p.190: §55)
(Morgoth's Ring, "The Later Quenta Silmarillion", "(II) The Second Phase: Of the Darkening of Valinor"; p.284: §55c)
The various versions are similar yet different. It appears that Tolkien's latest conception, though still very vague, views Ungoliant as a creature that came from the "Outer Darkness", and very probably a servant of Melkor, at one point, who then went rogue and left his service to live in Avathar, where he would later find her and re-enlist her aid. It is suggested, however, that the Valar had no knowledge of her, which complicates the picture. It does however seem clear that Ungoliant is quite different in her nature from the Nameless Things, at the very least.
From here we enter the realm of speculation, and there can be a great many ways to interpret the quotes above. Indeed it can even be interpreted that Ungoliant was some kind of alien! But my opinion is somewhat different.
There is an interesting passage in the Ainulindalë, that caught my eye some time ago:
(The Silmarillion, "Ainulindalë")
Thus the Valar and the Maiar were in fact only some of the Ainur, whereas the rest of them decided to remain with Eru outside of Eä.
Therefore it can even be theorised that Ungoliant was in fact an Ainu and was "one of those that [Melkor] had corrupted to his service". The Valar's ignorance of her can perhaps be explained in that they did not know what she had become, or perhaps they did not even know that she entered Eä to begin with - for it is said that she "had descended from the darkness that lies about Arda, when Melkor first looked down in envy upon the light in the kingdom of Manwë", and thus (within the scope of this theory) would not have been one of the Ainur that entered Eä at first, but rather decided to enter it later. By this reasoning, it may even be argued that Ungoliant, had she joined the Ainur who entered Eä originally rather than entering it later, might have been counted among the Valar herself - her ability to overpower Melkor, though 'fuelled' at the time by the power of the Two Trees that she had consumed, is a remarkable feat.
To clarify - Ungoliant is not a Vala. She is probably not a Maia either. And if we are to be perfectly honest, we really don't know what she is, and that is fun aspect of it... But perhaps, had her story been slightly different, she may have been a Vala (or at least a Maia); it is an interesting prospect, though speculative as it is.
Go on. Crucify me.