In The Hobbit, Bilbo meets Gollum in the Misty Mountains.
Bilbo becomes separated from Thorin’s company inside the mountain tunnels and finds a small golden ring. He then encounters Gollum, a solitary creature living on an island in an underground lake. The two compete in a riddle game, with Bilbo’s questions and Gollum’s answers determining whether Bilbo can escape.
Gollum originally possessed the ring before losing it to Bilbo. In The Lord of the Rings, Tolkien expanded Gollum’s history and established that his earlier name was Sméagol. The ring’s influence had transformed him physically and psychologically over many centuries.
Readers sometimes confuse Gollum with Shelob, the giant spider encountered much later by Frodo and Sam, or with the Balrog, the ancient demon beneath Moria. Those are separate creatures in Tolkien’s mythology, while Gollum is directly connected to the One Ring’s history.