Shelob Is Not the Most Appalling Monster Imaginable

Many people (myself included) might usually think of a gigantic spider as a disgusting monster that should be fought and destroyed. The truth is that Shelob isn’t a monster. Shelob and her ancestor, Ungoliant, were both used as tools by evil people, but are not evil themselves. She merely needs to eat and hunt like any other animal. The reason Frodo and Sam fought Shelob is because Gollum, the real monster in this case, led them to her.
Shelob is much like her ancestor, Ungoliant. Ungoliant and Shelob are both creatures that are able to change their shape, and settled with being spiders. Ungoliant’s idea of a feast was light and good objects. Melkor used this for his evil purposes when he had Ungoliant swallow Laurelin and Telperion, the Trees of Valinor. In this case, Melkor is more evil than Ungoliant because he wanted the Trees of Valinor destroyed, and Ungoliant wanted to eat. Even if Ungoliant hadn’t existed, Melkor would still have found some way of destroying the Trees of Valinor. If she had been left alone, Ungoliant would not have gone out of her way to go and eat the Trees of Valinor. She wanted to be left alone. In the Silmarillion, it says that she left Melkor's service to be her own master.
Gollum is an appalling monster in book four. During that book, he gained Frodo’s trust by leading them through the Dead Marshes and North Ithilien, but then betrays their trust by leading them through Cirith Ungol. Gollum led them to Shelob’s insatiable hunger, intending them to be killed and allowing him to retrieve the Ring. It is clear from this part of the book that Gollum doesn’t care about helping Frodo and Sam, and that he hasn’t changed. Gollum is full of selfish malice towards the Ring bearer, and would do anything to get the Ring back. Ungoliant and Shelob acted unaware of the impact their actions would have on Middle Earth. There was no malice or evil intent in either of them.
Although the giant spiders are meant to be horrible monsters imaginable, they are not the worst creatures in Tolkien’s writings. The real monsters of the Silmarillion and the Two Towers are Melkor and Gollum respectively. They showed complete selfishness and malice towards all of Middle Earth, whereas Ungoliant and Shelob were nothing but tools to work the evils of Melkor and Gollum.