Originally Ungoliant was going to be killed by Eärendil in the first age, this goes back to some of the very early pre-BoLT material, and was still present during the drafting of Bilbo's song at Rivendell.

Then Tolkien decided to change this, and bring Ungoliant back as an enemy for Frodo and Sam to meet in LotR. He then decided to make that one a different spider named Shelob, but kept the idea of Ungoliant surviving the First Age, passing out of known history. (In one late writing he says she "returned into the South of the world, where she abides yet for all that the Eldar have heard" and in a different one he says "whither she went after no tale tells. It is said that she ended long ago, when in her uttermost famine she devoured herself at last".)

I mean the big bad Sauron was defeated by an elf and a man. I love that power in Tolkiens world means so much more than battle prowess.

In The Hobbit, when they've been treed by goblins, Gandalf was going to jump out of the tree at them. It explicitly says that he probably would have been killed, but that he would have taken many of them with him. (Then the eagles arrive and rescue them.) Gandalf is also injured in the Battle of the Five Armies, wizard though he was. Gandalf can be threatened by orcs, not just maia or greater.

oh Sam would fuck that emo boy up. Edginess can't do nothing against grass-fed beef

For the love of god, YES! There’s been a swarm of “who’s more powerful” posts, and this place feels like a DBZ sub some days.

…although Sam would ruin Turin’s whole career

Right. An elf bloodied the most terrible being in middle-Earth. Sauron was defeated by a dog.

>Gandalf has only been shown to be truly afraid when he faces a maia or greater (Balrog, Saruman, Sauron).

Somebody has to keep repeating that Tolkien is not about power rankings (and endure the inevitable flurry of downvotes.

Turin would have been no match for Shelob. It says so in the book. Neither would Beren. It follows therefore that she had nothing at all to fear from a mere hobbit gardener. But guess what?

That’s where all the Magapublicans come from

I don't think Ungoliant is a maia. I think she's just the ancestor of all spiders, a mortal creature. She was just lucky in vexing Melkor in his most exhausted stage of life. Ordinarily she would not had stood a chance against Melkor.

In the two towers, Gandalf mentions creatures in the deep "the world is gnawed by nameless things. I will bring no report to darken the light of day."

Shelob, the daughter of Ungoliant, is compared often to darkness and extinguishing of light. Additionally, the word 'gnawed' is used. Gnawing usually occurs when one is hungry or dissatisfied, and how did Ungoliant die? Eating herself out of hunger.

Also, Gandalf has only been shown to be truly afraid when he faces a maia or greater (Balrog, Saruman, Sauron). And the only thing I can think of being down there, is maia corrupted by melkor who fled to the deeps, and it is shown that maia cannot die, so if Ungoliant is one (which is a common theory), she survived and is down there.

It's also very possible it's something darker, and not mentioned by Tolkien at all though.

Theory: Ungoliant is Alive