Shelob is the great spider that Samwise Gamgee fights in J.R.R. Tolkien’s The Lord of the Rings.
Shelob lives in Cirith Ungol, a pass near Mordor, and attacks Frodo Baggins and Sam during their journey toward Mount Doom. She poisons Frodo, but Sam uses the sword Sting and the Phial of Galadriel to drive her away.
Tolkien describes Shelob as an ancient descendant of Ungoliant, the monstrous spider-like being from the First Age. This connection makes Shelob more than an ordinary giant animal, although she is not presented as one of the Maiar or Valar.
Shelob appears in The Two Towers, near the end of the book. Her name means female spider in Tolkien’s constructed language usage and is not the name of a species.