Gollum says “My precious” in J.R.R. Tolkien’s The Hobbit.
Bilbo Baggins encounters Gollum beneath the Misty Mountains after becoming separated from the dwarves. Gollum lives beside an underground lake and possesses the One Ring, which he calls his “Precious.” During their famous riddle contest, Bilbo finds the Ring and unknowingly gains the power of invisibility.
Gollum was once a hobbit-like being named Sméagol. The Ring’s influence and his long isolation transformed him physically and psychologically. Tolkien develops this history further in The Lord of the Rings, where Gollum becomes central to the Ring’s eventual destruction.
Smaug, Shelob, and the Witch-king are also major Tolkien villains, but none is the character associated with this phrase. The wording is Gollum’s possessive nickname for the Ring, not the Ring’s formal name.