Tolkien and the Monsters

[Fordim Hedgethistle]

Little she knew of or cared for towers, or rings, or anything devised by mind or hand, who only desired death for all others, mind and body, and for herself a glut of life, alone, swollen till the mountains could no longer hold her up and the darkness could not contain her.

I would suggest that Shelob is far more that just a hungry 'beast'! Shelob's hunger is more than just the pangs of a being that needs sustenance. So great is her "lust" to consume "all others" that she is very much on par with Sauron:

So they both lived, delighting in their own devices, and feared no assault, nor wrath, nor any end to their wickedness.

The more I look at Shelob, the more I see her as Sauron's equal in evil -- she is just another form of evil. And now I am going to take a flier: Shelob is the manifestation of feminine (note: not female) evil, and Sauron of masculine. Shelob is the complete perversion of femininity and the 'ideals' of the feminine (as embodied by Arwen?): she consumes and feeds and gluts rather than nourishes. Sauron is the perversion of masculinity and the 'ideals' of the masculine (as embodied by Aragorn?): he seeks dominion and control rather than inspiring love through his willingness to sacrifice himself.