Shelob

[Kuruharan]

Shelob arrived later or was living elsewhere in the mountains and took up residency after the Gondorians vacated.

If she had been living somewhere else in the mountains where would that be? I would assume (her being a reclusive spider and all) that she would have been living someplace that was almost as concealed as in the tunnels below Cirith Ungol, yet have access to adequate supplies of easily snared food. Is it possible that she was from some other place entirely and moved there at a relatively late date?

But Shelob must have been eating something in all the centuries that Mordor was under the control of Gondor - maybe it was some poor men of Gondor.

It does say that no soldier of Old Gondor had been able to set blade to her, so I think that this is likely to be true.

That would push the date on a late arrival theory until after Gondor's occupation, but before they left. Perhaps the fall of Sauron allowed her to move through Mordor without attracting anyone's notice?

(Nice pic, Turambar)