Gollum

Gollum was an individual who once referred to a ring as "precious".

Biography
Gollum was in a cave when he noticed a ring, which he referred to as his "precious", running towards it before it was swiped away by Sonic the Hedgehog. (WC: New Adventures Await!)

Other references
"Gollum" was a name used by Rose Tyler to refer to Chip, the servant of Lady Cassandra O'Brien.Δ17. (TV: New Earth)

Clyde Langer called Commander Kaagh Gollum. (PROSE: The Last Sontaran)

Behind the scenes

 * Although not mentioned in the DWU, Gollum is a character from The Lord of the Rings.
 * Gollum appeared as a playable character in LEGO Dimensions.