From Ungoliant to Shelob (A History of Giant Spiders)

Ungoliant is the first spider you meet in the entire Middle Earth series. She is working under Melchor, but after destroying town and devouring anything she sees. She finishes her job for him, and wants a reward, but Melchor is afraid of her, but he reluctantly holds takes a Silmaril in his hand, but she eats it, and it drives her mad (I don't remember how he gets it back :/). Then there are the smaller spiders in The Hobbit. They are not as terrifying to read about, but to a hobbit and 13 dwarves, several of those spiders are quite frightening. They capture the heroes, but they miss Bilbo. He frees his companions and holds off the spiders with Sting. The last spider is Shelob, the terror at Cirith Ungol (the pass). She is not quite as big as Ungoliant, but almost as scary (definatly for Sam and Frodo). She guards the pass into Mordor and kills all who try to enter Mordor. Frodo gets captured, so Sam comes in to save him. He uses Sting to stab her belly. What happens after that, no one knows. We know Shelob was wounded, and we know she lived, but there is no other history about her.