The great spider who fought Samwise Gamgee in J.R.R. Tolkien’s mythology is Shelob.
Shelob appears in The Lord of the Rings when Frodo and Sam attempt to cross Cirith Ungol on their way into Mordor. She attacks Frodo, but Sam uses the sword Sting and the Phial of Galadriel to drive her away and rescue the quest’s mission.
Shelob is described as a descendant of Ungoliant, a much older and more powerful primordial spider from Tolkien’s mythology. This distinction is a common source of confusion: Ungoliant belongs to the First Age narratives, while Shelob is the creature encountered by Frodo and Sam in the Third Age.