Jungian archetypes
Patrick Grant, a scholar of Renaissance literature, saw Shelob and Galadriel's character pairing as fitting the opposition of Jungian archetypes. Frodo's anima is the Elf-queen Galadriel, who is opposed by the evil giant female spider Shelob. Frodo's Shadow is the male Hobbit Gollum. All of these, along with oppositions between other characters in the story, create an image of the self.