In The Hobbit, Gollum plays a riddle game with Bilbo Baggins. Their encounter takes place beneath the Misty Mountains after Bilbo becomes separated from the dwarf company.
Gollum lives on a small island in an underground lake. He possesses a mysterious golden ring, which Bilbo finds after escaping from the cave. The riddle contest gives Bilbo a way to delay Gollum while he searches for a route out.
Gollum was once a hobbit-like creature named Sméagol. The Ring’s influence and his long isolation transformed him physically and psychologically. In The Lord of the Rings, his obsession with the Ring becomes central to the plot and ultimately helps bring about its destruction.
Gollum is sometimes mistakenly identified as an orc, goblin, or ordinary hobbit. Tolkien’s texts instead describe him as a corrupted relative of the hobbits, with a history tied to the Stoor branch.